1
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Lv D, Chen X, Jiang N, Wang G, Zeng X, Fang W, Li W, Zhou M. A rotational spectroscopy study of microsolvation effects on intramolecular proton transfer in trifluoroacetylacetone-(H 2O) 1-3. Phys Chem Chem Phys 2024; 26:12530-12536. [PMID: 38619876 DOI: 10.1039/d4cp01061b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Trifluoroacetylacetone (TFAA) has two enol forms, which can switch to each other via proton transfer. While much attention has been paid to their conformational preferences, the influence of microsolvation on regulating the proton position remains unexplored. Herein, we report the rotational spectra of trifluoroacetylacetone-(water)n (n = 1-3) investigated by chirped pulse Fourier transform microwave spectroscopy in the 2-8 GHz frequency range. Two conformers were identified for both TFAA-H2O and TFAA-(H2O)2, while only one conformer was characterized for TFAA-(H2O)3. The results indicate that water binding on the CH3 side stabilizes the enolF form, whereas water binding on the CF3 side stabilizes the enolH form. The enolF form predominates over the enolH form in these hydrated complexes, which contrasts with the fact that only enolH exists in isolated TFAA. EnolH becomes preferred only when water inserts itself into the intramolecular hydrogen bond. Instanton theory calculations reveal that the proton transfer reaction is dominated by quantum tunneling at low temperatures, leading to the stable existence of only one enol form in each configuration of the hydrated clusters.
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Affiliation(s)
- Dingding Lv
- Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438 Shanghai, China.
| | - Xinlei Chen
- Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438 Shanghai, China.
| | - Ningjing Jiang
- Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438 Shanghai, China.
| | - Guanjun Wang
- Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438 Shanghai, China.
| | - Xiaoqing Zeng
- Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438 Shanghai, China.
| | - Wei Fang
- Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438 Shanghai, China.
| | - Weixing Li
- Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438 Shanghai, China.
| | - Mingfei Zhou
- Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Songhu Rd. 2005, 200438 Shanghai, China.
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2
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Gu Y, Yong H, Gu B, Mukamel S. Chemical bond reorganization in intramolecular proton transfer revealed by ultrafast X-ray photoelectron spectroscopy. Proc Natl Acad Sci U S A 2024; 121:e2321343121. [PMID: 38635639 PMCID: PMC11046627 DOI: 10.1073/pnas.2321343121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 03/21/2024] [Indexed: 04/20/2024] Open
Abstract
Time-resolved X-ray photoelectron spectroscopy (TR-XPS) is used in a simulation study to monitor the excited state intramolecular proton transfer between oxygen and nitrogen atoms in 2-(iminomethyl)phenol. Real-time monitoring of the chemical bond breaking and forming processes is obtained through the time evolution of excited-state chemical shifts. By employing individual atomic probes of the proton donor and acceptor atoms, we predict distinct signals with opposite chemical shifts of the donor and acceptor groups during proton transfer. Details of the ultrafast bond breaking and forming dynamics are revealed by extending the classical electron spectroscopy chemical analysis to real time. Through a comparison with simulated time-resolved photoelectron spectroscopy at the valence level, the distinct advantage of TR-XPS is demonstrated thanks to its atom specificity.
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Affiliation(s)
- Yonghao Gu
- Department of Chemistry, University of California, Irvine, CA92697-2025
- Department of Physics and Astronomy, University of California, Irvine, CA92697-2025
| | - Haiwang Yong
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA92093
| | - Bing Gu
- Department of Chemistry, Westlake University, Hangzhou, Zhejiang310030, China
| | - Shaul Mukamel
- Department of Chemistry, University of California, Irvine, CA92697-2025
- Department of Physics and Astronomy, University of California, Irvine, CA92697-2025
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3
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Zhu S, Yang R, Li HJW, Huang S, Wang H, Liu Y, Li H, Zhai T. Reconstructing Hydrogen-Bond Network for Efficient Acidic Oxygen Evolution. Angew Chem Int Ed Engl 2024; 63:e202319462. [PMID: 38286750 DOI: 10.1002/anie.202319462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 01/31/2024]
Abstract
Developing highly active oxygen evolution reaction (OER) catalysts in acidic conditions is a pressing demand for proton-exchange membrane water electrolysis. Manipulating proton character at the electrified interface, as the crux of all proton-coupled electrochemical reactions, is highly desirable but elusive. Herein we present a promising protocol, which reconstructs a connected hydrogen-bond network between the catalyst-electrolyte interface by coupling hydrophilic units to boost acidic OER activity. Modelling on N-doped-carbon-layer clothed Mn-doped-Co3O4 (Mn-Co3O4@CN), we unravel that the hydrogen-bond interaction between CN units and H2O molecule not only drags the free water to enrich the surface of Mn-Co3O4 but also serves as a channel to promote the dehydrogenation process. Meanwhile, the modulated local charge of the Co sites from CN units/Mn dopant lowers the OER barrier. Therefore, Mn-Co3O4@CN surpasses RuO2 at high current density (100 mA cm-2 @ ~538 mV).
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Affiliation(s)
- Shicheng Zhu
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, P. R. China
| | - Ruoou Yang
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, P. R. China
| | - Huang Jing Wei Li
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, P. R. China
| | - Sirui Huang
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, P. R. China
| | - Haozhi Wang
- State Key Laboratory of Marine Resource Utilization in South China Sea, and School of Materials Science and Engineering, Hainan University, Haikou, Hainan, 570228, P. R. China
| | - Youwen Liu
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, P. R. China
| | - Huiqiao Li
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, P. R. China
| | - Tianyou Zhai
- State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, P. R. China
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4
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Zhao J, Yu P, Dong T, Wu Y, Yang F, Wang J. Chasing weakly-bound biological water in aqueous environment near the peptide backbone by ultrafast 2D infrared spectroscopy. Commun Chem 2024; 7:82. [PMID: 38605209 PMCID: PMC11009226 DOI: 10.1038/s42004-024-01170-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Accepted: 04/05/2024] [Indexed: 04/13/2024] Open
Abstract
There has been a long-standing debate as to how many hydrogen bonds a peptide backbone amide can form in aqueous solution. Hydrogen-bonding structural dynamics of N-ethylpropionamide (a β-peptide model) in water was examined using infrared (IR) spectroscopy. Two amide-I sub bands arise mainly from amide C=O group that forms strong H-bonds with solvent water molecules (SHB state), and minorly from that involving one weak H-bond with water (WHB state). This picture is supported by molecular dynamics simulations and ab-initio calculations. Further, thermodynamics and kinetics of the SHB and WHB species were examined mainly by chemical-exchange two-dimensional IR spectroscopy, yielding an activation energy for the SHB-to-WHB exchange of 13.25 ± 0.52 kJ mol‒1, which occurs in half picosecond at room temperature. Our results provided experimental evidence of an unstable water molecule near peptide backbone, allowing us to gain more insights into the dynamics of the protein backbone hydration.
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Affiliation(s)
- Juan Zhao
- Molecular Reaction Dynamics Laboratory, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Pengyun Yu
- Molecular Reaction Dynamics Laboratory, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Tiantian Dong
- Molecular Reaction Dynamics Laboratory, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yanzhou Wu
- Molecular Reaction Dynamics Laboratory, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Fan Yang
- Molecular Reaction Dynamics Laboratory, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jianping Wang
- Molecular Reaction Dynamics Laboratory, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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5
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Deng J, Cui Q. Efficient Sampling of Cavity Hydration in Proteins with Nonequilibrium Grand Canonical Monte Carlo and Polarizable Force Fields. J Chem Theory Comput 2024; 20:1897-1911. [PMID: 38417108 DOI: 10.1021/acs.jctc.4c00013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2024]
Abstract
Prediction of the hydration levels of protein cavities and active sites is important to both mechanistic analysis and ligand design. Due to the unique microscopic environment of these buried water molecules, a polarizable model is expected to be crucial for an accurate treatment of protein internal hydration in simulations. Here we adapt a nonequilibrium candidate Monte Carlo approach for conducting grand canonical Monte Carlo simulations with the Drude polarizable force field. The GPU implementation enables the efficient sampling of internal cavity hydration levels in biomolecular systems. We also develop an enhanced sampling approach referred to as B-walking, which satisfies detailed balance and readily combines with grand canonical integration to efficiently calculate quantitative binding free energies of water to protein cavities. Applications of these developments are illustrated in a solvent box and the polar ligand binding site in trypsin. Our simulation results show that including electronic polarization leads to a modest but clear improvement in the description of water position and occupancy compared to the crystal structure. The B-walking approach enhances the range of water sampling in different chemical potential windows and thus improves the accuracy of water binding free energy calculations.
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Affiliation(s)
- Jiahua Deng
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Qiang Cui
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
- Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, Massachusetts 02215, United States
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6
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Hirata K, Akasaka K, Dopfer O, Ishiuchi SI, Fujii M. Transition from vehicle to Grotthuss proton transfer in a nanosized flask: cryogenic ion spectroscopy of protonated p-aminobenzoic acid solvated with D 2O. Chem Sci 2024; 15:2725-2730. [PMID: 38404372 PMCID: PMC10882521 DOI: 10.1039/d3sc05455a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 01/18/2024] [Indexed: 02/27/2024] Open
Abstract
Proton transfer (PT) is one of the most ubiquitous reactions in chemistry and life science. The unique nature of PT has been rationalized not by the transport of a solvated proton (vehicle mechanism) but by the Grotthuss mechanism in which a proton is transported to the nearest proton acceptor along a hydrogen-bonded network. However, clear experimental evidence of the Grotthuss mechanism has not been reported yet. Herein we show by infrared spectroscopy that a vehicle-type PT occurs in the penta- and hexahydrated clusters of protonated p-aminobenzoic acid, while Grotthuss-type PT is observed in heptahydrated clusters, indicating a change in the PT mechanism depending on the degree of hydration. These findings emphasize the importance of the usually ignored vehicle mechanism as well as the degree of hydration. It highlights the possibility of controlling the PT mechanism by the number of water molecules in chemical and biological environments.
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Affiliation(s)
- Keisuke Hirata
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
- Department of Chemistry, School of Science, Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku Tokyo 152-8550 Japan
- International Research Frontiers Initiative, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
| | - Kyota Akasaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
- School of Life Science and Technology, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama Kanagawa 226-8503 Japan
| | - Otto Dopfer
- International Research Frontiers Initiative, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
- Institut für Optik und Atomare Physik, Technische Universität Berlin Hardenbergstrasse 36 10623 Berlin Germany
| | - Shun-Ichi Ishiuchi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
- Department of Chemistry, School of Science, Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku Tokyo 152-8550 Japan
- International Research Frontiers Initiative, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
| | - Masaaki Fujii
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
- School of Life Science and Technology, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama Kanagawa 226-8503 Japan
- International Research Frontiers Initiative, Tokyo Institute of Technology 4259 Nagatsuta-cho, Midori-ku Yokohama 226-8503 Japan
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7
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Tomida S, Wada A, Furutani Y. Protonation of Asp116 and distortion of the all-trans retinal chromophore in Krokinobacter eikastus rhodopsin 2 causes a redshift in absorption maximum upon dehydration. Photochem Photobiol Sci 2023; 22:2499-2517. [PMID: 37498510 DOI: 10.1007/s43630-023-00464-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 07/19/2023] [Indexed: 07/28/2023]
Abstract
Water is usually indispensable for protein function. For ion-pumping rhodopsins, water molecules inside the proteins play an important role in ion transportation. In addition to amino acid residues, water molecules regulate the colors of retinal proteins. It was reported that a sodium-pumping rhodopsin, Krokinobacter eikastus rhodopsin 2 (KR2), showed a color change from red to purple upon dehydration under crystalline conditions. Here, we applied comprehensive visible and IR absorption spectroscopy and resonance Raman spectroscopy to KR2 in liposomes under hydration-controlled conditions. A large increase in the hydrogen-out-of-plane (HOOP) vibration at 947 (H-C11=C12-H Au mode) and moderate increases at 893 (C7-H and C10-H) and 808 (C14-H) cm-1 were observed under dehydrated conditions, which were assigned by using systematically deuterated retinal. Moreover, the Asn variant at Asp116, which functions as a counter ion for the protonated retinal Schiff base (PRSB), caused a large redshift in the absorption maximum and constitutive increase in the HOOP modes under hydrated and dehydrated conditions. The protonation of a counter ion at Asp116 clearly causes a redshift in the absorption maximum as the all-trans retinal chromophore twists upon dehydration. Namely, the results strongly suggested that water molecules are important for maintaining the hydrogen-bonding network at the PRSB and deprotonation state of Asp116 in KR2.
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Affiliation(s)
- Sahoko Tomida
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan
| | - Akimori Wada
- Laboratory of Organic Chemistry for Life Science, Kobe Pharmaceutical University, Higashinada-ku, Kobe, 658-8558, Japan
| | - Yuji Furutani
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan.
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan.
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8
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Yang Q, Chen D. Na + Binding and Transport: Insights from Light-Driven Na +-Pumping Rhodopsin. Molecules 2023; 28:7135. [PMID: 37894614 PMCID: PMC10608830 DOI: 10.3390/molecules28207135] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/07/2023] [Accepted: 10/16/2023] [Indexed: 10/29/2023] Open
Abstract
Na+ plays a vital role in numerous physiological processes across humans and animals, necessitating a comprehensive understanding of Na+ transmembrane transport. Among the various Na+ pumps and channels, light-driven Na+-pumping rhodopsin (NaR) has emerged as a noteworthy model in this field. This review offers a concise overview of the structural and functional studies conducted on NaR, encompassing ground/intermediate-state structures and photocycle kinetics. The primary focus lies in addressing key inquiries: (1) unraveling the translocation pathway of Na+; (2) examining the role of structural changes within the photocycle, particularly in the O state, in facilitating Na+ transport; and (3) investigating the timing of Na+ uptake/release. By delving into these unresolved issues and existing debates, this review aims to shed light on the future direction of Na+ pump research.
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Affiliation(s)
- Qifan Yang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Deliang Chen
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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9
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Helbing J, Hamm P. Versatile Femtosecond Laser Synchronization for Multiple-Timescale Transient Infrared Spectroscopy. J Phys Chem A 2023. [PMID: 37478282 DOI: 10.1021/acs.jpca.3c03526] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2023]
Abstract
Several ways to electronically synchronize different types of amplified femtosecond laser systems are presented based on a single freely programmable electronics hardware: arbitrary-detuning asynchronous optical sampling (ADASOPS), as well as actively locking two femtosecond laser oscillators, albeit not necessarily to the same round-trip frequency. They allow us to rapidly probe a very wide range of timescales, from picoseconds to potentially seconds, in a single transient absorption experiment without the need to move any delay stage. Experiments become possible that address a largely unexplored aspect of many photochemical reactions, in particular in the context of photo-catalysis as well as photoactive proteins, where an initial femtosecond trigger very often initiates a long-lasting cascade of follow-up processes. The approach is very versatile and allows us to synchronize very different lasers, such as a Ti:Sa amplifier and a 100 kHz Yb-laser system. The jitter of the synchronization, and therewith the time-resolution in the transient experiment, lies in the range from 1 to 3 ps, depending on the method. For illustration, transient IR measurements of the excited state solvation and decay of a metal carbonyl complex as well as the full reaction cycle of bacteriorhodopsin are shown. The pros and cons of the various methods are discussed, with regard to the scientific question one might want to address, and also with regard to the laser systems that might be already existent in a laser lab.
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Affiliation(s)
- Jan Helbing
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Peter Hamm
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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10
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Kratochvil HT, Watkins LC, Mravic M, Thomaston JL, Nicoludis JM, Somberg NH, Liu L, Hong M, Voth GA, DeGrado WF. Transient water wires mediate selective proton transport in designed channel proteins. Nat Chem 2023; 15:1012-1021. [PMID: 37308712 PMCID: PMC10475958 DOI: 10.1038/s41557-023-01210-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 04/19/2023] [Indexed: 06/14/2023]
Abstract
Selective proton transport through proteins is essential for forming and using proton gradients in cells. Protons are conducted along hydrogen-bonded 'wires' of water molecules and polar side chains, which, somewhat surprisingly, are often interrupted by dry apolar stretches in the conduction pathways, inferred from static protein structures. Here we hypothesize that protons are conducted through such dry spots by forming transient water wires, often highly correlated with the presence of the excess protons in the water wire. To test this hypothesis, we performed molecular dynamics simulations to design transmembrane channels with stable water pockets interspersed by apolar segments capable of forming flickering water wires. The minimalist designed channels conduct protons at rates similar to viral proton channels, and they are at least 106-fold more selective for H+ over Na+. These studies inform the mechanisms of biological proton conduction and the principles for engineering proton-conductive materials.
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Affiliation(s)
- Huong T Kratochvil
- Department of Pharmaceutical Chemistry, University of California-San Francisco, San Francisco, CA, USA.
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Laura C Watkins
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics and James Franck Institute, The University of Chicago, Chicago, IL, USA
- Kemper Insurance, Chicago, IL, USA
| | - Marco Mravic
- Department of Pharmaceutical Chemistry, University of California-San Francisco, San Francisco, CA, USA
- Department of Integrative Structural and Computational Biology Scripps Research Institute, La Jolla, CA, USA
| | - Jessica L Thomaston
- Department of Pharmaceutical Chemistry, University of California-San Francisco, San Francisco, CA, USA
| | - John M Nicoludis
- Department of Pharmaceutical Chemistry, University of California-San Francisco, San Francisco, CA, USA
- Genentech, San Francisco, CA, USA
| | - Noah H Somberg
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Gregory A Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics and James Franck Institute, The University of Chicago, Chicago, IL, USA.
| | - William F DeGrado
- Department of Pharmaceutical Chemistry, University of California-San Francisco, San Francisco, CA, USA.
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11
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Kubař T, Elstner M, Cui Q. Hybrid Quantum Mechanical/Molecular Mechanical Methods For Studying Energy Transduction in Biomolecular Machines. Annu Rev Biophys 2023; 52:525-551. [PMID: 36791746 PMCID: PMC10810093 DOI: 10.1146/annurev-biophys-111622-091140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Hybrid quantum mechanical/molecular mechanical (QM/MM) methods have become indispensable tools for the study of biomolecules. In this article, we briefly review the basic methodological details of QM/MM approaches and discuss their applications to various energy transduction problems in biomolecular machines, such as long-range proton transports, fast electron transfers, and mechanochemical coupling. We highlight the particular importance for these applications of balancing computational efficiency and accuracy. Using several recent examples, we illustrate the value and limitations of QM/MM methodologies for both ground and excited states, as well as strategies for calibrating them in specific applications. We conclude with brief comments on several areas that can benefit from further efforts to make QM/MM analyses more quantitative and applicable to increasingly complex biological problems.
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Affiliation(s)
- T Kubař
- Institute of Physical Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany;
| | - M Elstner
- Institute of Physical Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany;
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, Karlsruhe, Germany;
| | - Q Cui
- Department of Chemistry, Boston University, Boston, Massachusetts, USA;
- Department of Physics, Boston University, Boston, Massachusetts, USA
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA
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12
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Furutani Y, Yang CS. Ion-transporting mechanism in microbial rhodopsins: Mini-review relating to the session 5 at the 19th International Conference on Retinal Proteins. Biophys Physicobiol 2023; 20:e201005. [PMID: 38362333 PMCID: PMC10865854 DOI: 10.2142/biophysico.bppb-v20.s005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 01/06/2023] [Indexed: 01/11/2023] Open
Affiliation(s)
- Yuji Furutani
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Aichi 466-8555, Japan
| | - Chii-Shen Yang
- Department of Biochemical Science and Technology, National Taiwan University, Taipei 10617, Taiwan
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13
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Yang XD, Zhou JH, Cui JW, Yang J, Jia HP, Sun JK, Zhang J. Long-Lived Multiple Charge Separation by Proton-Coupled Electron Transfer. Angew Chem Int Ed Engl 2023; 62:e202215591. [PMID: 36691958 DOI: 10.1002/anie.202215591] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 01/23/2023] [Accepted: 01/23/2023] [Indexed: 01/25/2023]
Abstract
Multiple charge separation has been successfully realized by a proton-coupled electron transfer reaction in an organic cocrystal. Benefiting from the adjustable electronic energy level of the electron donor and acceptor through thermal-induced proton migration, distinct optical absorption behaviors combined with color changes to blue or green are observed in these charge-separated states. It is of interest to note that such charge-separated states exhibit a longer lifetime of over a month as a result of the excellent coplanarity and π-π interaction of the electron acceptors. Moreover, the enhanced absorption toward longer wavelengths endows the charge-separated state with near-infrared (808 nm) photothermal conversion for imaging and bacterial inhibition, whereby the conversion performance can be controlled by the degree of proton migration.
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Affiliation(s)
- Xiao-Dong Yang
- MOE Key Laboratory of Cluster Science, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 102488, P. R. China
| | - Jun-Hao Zhou
- MOE Key Laboratory of Cluster Science, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 102488, P. R. China
| | - Jing-Wang Cui
- MOE Key Laboratory of Cluster Science, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 102488, P. R. China
| | - Jie Yang
- MOE Key Laboratory of Cluster Science, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 102488, P. R. China
| | - Hong-Peng Jia
- Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, P. R. China
| | - Jian-Ke Sun
- MOE Key Laboratory of Cluster Science, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 102488, P. R. China
| | - Jie Zhang
- MOE Key Laboratory of Cluster Science, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 102488, P. R. China
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14
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Hofmann KP, Lamb TD. Rhodopsin, light-sensor of vision. Prog Retin Eye Res 2023; 93:101116. [PMID: 36273969 DOI: 10.1016/j.preteyeres.2022.101116] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 08/20/2022] [Accepted: 08/22/2022] [Indexed: 11/06/2022]
Abstract
The light sensor of vertebrate scotopic (low-light) vision, rhodopsin, is a G-protein-coupled receptor comprising a polypeptide chain with bound chromophore, 11-cis-retinal, that exhibits remarkable physicochemical properties. This photopigment is extremely stable in the dark, yet its chromophore isomerises upon photon absorption with 70% efficiency, enabling the activation of its G-protein, transducin, with high efficiency. Rhodopsin's photochemical and biochemical activities occur over very different time-scales: the energy of retinaldehyde's excited state is stored in <1 ps in retinal-protein interactions, but it takes milliseconds for the catalytically active state to form, and many tens of minutes for the resting state to be restored. In this review, we describe the properties of rhodopsin and its role in rod phototransduction. We first introduce rhodopsin's gross structural features, its evolution, and the basic mechanisms of its activation. We then discuss light absorption and spectral sensitivity, photoreceptor electrical responses that result from the activity of individual rhodopsin molecules, and recovery of rhodopsin and the visual system from intense bleaching exposures. We then provide a detailed examination of rhodopsin's molecular structure and function, first in its dark state, and then in the active Meta states that govern its interactions with transducin, rhodopsin kinase and arrestin. While it is clear that rhodopsin's molecular properties are exquisitely honed for phototransduction, from starlight to dawn/dusk intensity levels, our understanding of how its molecular interactions determine the properties of scotopic vision remains incomplete. We describe potential future directions of research, and outline several major problems that remain to be solved.
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Affiliation(s)
- Klaus Peter Hofmann
- Institut für Medizinische Physik und Biophysik (CC2), Charité, and, Zentrum für Biophysik und Bioinformatik, Humboldt-Unversität zu Berlin, Berlin, 10117, Germany.
| | - Trevor D Lamb
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT 2600, Australia.
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15
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My remembrances of H.G. Khorana: exploring the mechanism of bacteriorhodopsin with site-directed mutagenesis and FTIR difference spectroscopy. Biophys Rev 2023; 15:103-110. [PMID: 36909952 PMCID: PMC9995631 DOI: 10.1007/s12551-023-01046-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 01/23/2023] [Indexed: 02/09/2023] Open
Abstract
H.G. Khorana's seminal contributions to molecular biology are well-known. He also had a lesser known but still major influence on current application of advanced vibrational spectroscopic techniques such as FTIR difference spectroscopy to explore the mechanism of bacteriorhodopsin and other integral membrane proteins. In this review, I provide a personal perspective of my collaborative research and interactions with Gobind, from 1982 to 1995 when our groups published over 25 papers together which resulted in an early picture of key features of the bacteriorhodopsin proton pump mechanism. Much of this early work served as a blueprint for subsequent advances based on combining protein bioengineering and vibrational spectroscopic techniques to study integral membrane proteins.
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16
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Interdisciplinary biophysical studies of membrane proteins bacteriorhodopsin and rhodopsin. Biophys Rev 2023; 15:111-125. [PMID: 36909961 PMCID: PMC9995646 DOI: 10.1007/s12551-022-01003-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 09/28/2022] [Indexed: 10/10/2022] Open
Abstract
The centenary of the birth of H. Gobind Khorana provides an auspicious opportunity to review the origins and evolution of parallel advances in biophysical methodology and molecular genetics technology used to study membrane proteins. Interdisciplinary work in the Khorana laboratory in the late 1970s and for the next three decades led to productive collaborations and fostered three subsequent scientific generations whose biophysical work on membrane proteins has led to detailed elucidation of the molecular mechanisms of energy transduction by the light-driven proton pump bacteriorhodopsin (bR) and signal transduction by the G protein-coupled receptor (GPCR) rhodopsin. This review will highlight the origins and advances of biophysical studies of membrane proteins made possible by the application of molecular genetics approaches to engineer site-specific alterations of membrane protein structures.
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17
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Tsujimura M, Chiba Y, Saito K, Ishikita H. Proton transfer and conformational changes along the hydrogen bond network in heliorhodopsin. Commun Biol 2022; 5:1336. [PMID: 36474019 PMCID: PMC9726877 DOI: 10.1038/s42003-022-04311-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022] Open
Abstract
Heliorhodopsin releases a proton from the Schiff base during the L-state to M-state transition but not toward the protein bulk surface. Here we investigate proton transfer and induced structural changes along the H-bond network in heliorhodopsin using a quantum mechanical/molecular mechanical approach and molecular dynamics simulations. Light-induced proton transfer could occur from the Schiff base toward Glu107, reorienting Ser76, followed by subsequent proton transfer toward His80. His80 protonation induces the reorientation of Trp246 on the extracellular surface, originating from the electrostatic interaction that propagates along the transmembrane H-bond network [His80…His23…H2O[H23/Q26]…Gln26…Trp246] over a distance of 15 Å. Furthermore, it induces structural fluctuation on the intracellular side in the H-bond network [His80…Asn16…Tyr92…Glu230…Arg104…Glu149], opening the inner cavity at the Tyr92 moiety. These may be a basis of how light-induced proton transfer causes conformational changes during the M-state to O-state transition.
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Affiliation(s)
- Masaki Tsujimura
- grid.26999.3d0000 0001 2151 536XDepartment of Advanced Interdisciplinary Studies, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 Japan
| | - Yoshihiro Chiba
- grid.26999.3d0000 0001 2151 536XDepartment of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654 Japan
| | - Keisuke Saito
- grid.26999.3d0000 0001 2151 536XDepartment of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654 Japan ,grid.26999.3d0000 0001 2151 536XResearch Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 Japan
| | - Hiroshi Ishikita
- grid.26999.3d0000 0001 2151 536XDepartment of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654 Japan ,grid.26999.3d0000 0001 2151 536XResearch Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 Japan
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18
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Shi B, Pang X, Li S, Wu H, Shen J, Wang X, Fan C, Cao L, Zhu T, Qiu M, Yin Z, Kong Y, Liu Y, Zhang M, Liu Y, Pan F, Jiang Z. Short hydrogen-bond network confined on COF surfaces enables ultrahigh proton conductivity. Nat Commun 2022; 13:6666. [PMID: 36335107 PMCID: PMC9637196 DOI: 10.1038/s41467-022-33868-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 10/05/2022] [Indexed: 11/07/2022] Open
Abstract
The idea of spatial confinement has gained widespread interest in myriad applications. Especially, the confined short hydrogen-bond (SHB) network could afford an attractive opportunity to enable proton transfer in a nearly barrierless manner, but its practical implementation has been challenging. Herein, we report a SHB network confined on the surface of ionic covalent organic framework (COF) membranes decorated by densely and uniformly distributed hydrophilic ligands. Combined experimental and theoretical evidences have pointed to the confinement of water molecules allocated to each ligand, achieving the local enrichment of hydronium ions and the concomitant formation of SHBs in water-hydronium domains. These overlapped water-hydronium domains create an interconnected SHB network, which yields an unprecedented ultrahigh proton conductivity of 1389 mS cm−1 at 90 °C, 100% relative humidity. When hydronium ions are enriched in confined water, short hydrogen bonds (SHBs) form due to the constrained space of excess protons between pairs of water molecules. Here authors demonstrate a SHB network confined on the surface of ionic COF membranes with tunable -SO3H groups, with proton conductivity of 1389 mS cm-1 at 90 oC.
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Affiliation(s)
- Benbing Shi
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China
| | - Xiao Pang
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China
| | - Shunning Li
- School of Advanced Materials, Peking University Shenzhen Graduate School, 518055, Shenzhen, Guangdong, China
| | - Hong Wu
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China.,Haihe Laboratory of Sustainable Chemical Transformations, 300192, Tianjin, China
| | - Jianliang Shen
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China
| | - Xiaoyao Wang
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China
| | - Chunyang Fan
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China
| | - Li Cao
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China
| | - Tianhao Zhu
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China
| | - Ming Qiu
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China
| | - Zhuoyu Yin
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China
| | - Yan Kong
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China
| | - Yiqin Liu
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China
| | - Mingzheng Zhang
- School of Advanced Materials, Peking University Shenzhen Graduate School, 518055, Shenzhen, Guangdong, China
| | - Yawei Liu
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, 100190, Beijing, China
| | - Feng Pan
- School of Advanced Materials, Peking University Shenzhen Graduate School, 518055, Shenzhen, Guangdong, China.
| | - Zhongyi Jiang
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, China. .,Haihe Laboratory of Sustainable Chemical Transformations, 300192, Tianjin, China. .,Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, 350207, Fuzhou, China. .,Zhejiang Institute of Tianjin University, 315201, Ningbo, Zhejiang, China.
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19
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Protons in Gating the Kv1.2 Channel: A Calculated Set of Protonation States in Response to Polarization/Depolarization of the Channel, with the Complete Proposed Proton Path from Voltage Sensing Domain to Gate. MEMBRANES 2022; 12:membranes12070718. [PMID: 35877921 PMCID: PMC9318985 DOI: 10.3390/membranes12070718] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 07/07/2022] [Accepted: 07/08/2022] [Indexed: 12/04/2022]
Abstract
We have in the past proposed that proton motion constitutes the gating current in the potassium channel Kv1.2 and is responsible for the gating mechanism. For this to happen, there must be a proton path between the voltage-sensing domain (VSD) and the channel gate, and here we present quantum calculations that lead to a specific pair of proton paths, defined at the molecular level, with well-defined water molecule linkages, and with hydrogen bonding between residues; there is also at least one interpath crossover, where protons can switch paths. Quantum calculations on the entire 563-atom system give the complete geometry, the energy, and atomic charges. Calculations show that three specific residues (in the pdb 3Lut numbering, H418, E327, R326), and the T1 intracellular moiety, all of which have been shown experimentally to be involved in gating, would necessarily be protonated or deprotonated in the path between the VSD and the gate. Hydroxyl reorientation of serine and threonine residues are shown to provide a means of adjusting proton directions of motion. In the deprotonated state for K312, a low energy state, our calculations come close to reproducing the X-ray structure. The demonstration of the existence of a double proton path between VSD and gate supports the proposed proton gating mechanism; when combined with our earlier demonstration of proton generation in the VSD, and comparison with other systems that are known to move protons, we are close to achieving the definition of a complete gating mechanism in molecular detail. The coupling of the paths to the VSD, and to the PVPV section that essentially forms the gate, can be easily seen from the results of the calculation. The gate itself remains for further computations.
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20
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Yu Y, Yang C, Baggioli M, Phillips AE, Zaccone A, Zhang L, Kajimoto R, Nakamura M, Yu D, Hong L. The ω 3 scaling of the vibrational density of states in quasi-2D nanoconfined solids. Nat Commun 2022; 13:3649. [PMID: 35752735 PMCID: PMC9233700 DOI: 10.1038/s41467-022-31349-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 06/14/2022] [Indexed: 11/25/2022] Open
Abstract
The vibrational properties of crystalline bulk materials are well described by Debye theory, which successfully predicts the quadratic ω2 low-frequency scaling of the vibrational density of states. However, the analogous framework for nanoconfined materials with fewer degrees of freedom has been far less well explored. Using inelastic neutron scattering, we characterize the vibrational density of states of amorphous ice confined inside graphene oxide membranes and we observe a crossover from the Debye ω2 scaling to an anomalous ω3 behaviour upon reducing the confinement size L. Additionally, using molecular dynamics simulations, we confirm the experimental findings and prove that such a scaling appears in both crystalline and amorphous solids under slab-confinement. We theoretically demonstrate that this low-frequency ω3 law results from the geometric constraints on the momentum phase space induced by confinement along one spatial direction. Finally, we predict that the Debye scaling reappears at a characteristic frequency ω× = vL/2π, with v the speed of sound of the material, and we confirm this quantitative estimate with simulations. A description of the vibrational properties of amorphous ice confined in graphene oxide membranes, as an exemplary nanoconfined material, is presented. Inelastic neutron scattering experiments and molecular dynamics simulations show anomalous deviations from standard bulk behavior.
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Affiliation(s)
- Yuanxi Yu
- School of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China.,Institute of Natural Sciences, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Chenxing Yang
- School of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China.,Institute of Natural Sciences, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Matteo Baggioli
- Wilczek Quantum Center, School of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China. .,Shanghai Research Center for Quantum Sciences, 201315, Shanghai, China.
| | - Anthony E Phillips
- School of Physics and Astronomy, Queen Mary University of London, London, UK
| | - Alessio Zaccone
- Department of Physics "A. Pontremoli", University of Milan, via Celoria 16, 20133, Milan, Italy.,Cavendish Laboratory, University of Cambridge, CB3 0HE, Cambridge, UK
| | - Lei Zhang
- Institute of Natural Sciences, Shanghai Jiao Tong University, 200240, Shanghai, China.,School of Materials Science and Engineering, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Ryoichi Kajimoto
- J-PARC Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki, 319-1195, Japan
| | - Mitsutaka Nakamura
- J-PARC Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki, 319-1195, Japan
| | - Dehong Yu
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - Liang Hong
- School of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China. .,Institute of Natural Sciences, Shanghai Jiao Tong University, 200240, Shanghai, China. .,Shanghai National Center for Applied Mathematics (SJTU Center), Shanghai Jiao Tong University, 200240, Shanghai, China. .,Shanghai Artificial Intelligence Laboratory, 200232, Shanghai, China. .,School of Medicine, Shanghai Jiao Tong University, 200240, Shanghai, China. .,Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, 200240, Shanghai, China.
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21
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de Grip WJ, Ganapathy S. Rhodopsins: An Excitingly Versatile Protein Species for Research, Development and Creative Engineering. Front Chem 2022; 10:879609. [PMID: 35815212 PMCID: PMC9257189 DOI: 10.3389/fchem.2022.879609] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 05/16/2022] [Indexed: 01/17/2023] Open
Abstract
The first member and eponym of the rhodopsin family was identified in the 1930s as the visual pigment of the rod photoreceptor cell in the animal retina. It was found to be a membrane protein, owing its photosensitivity to the presence of a covalently bound chromophoric group. This group, derived from vitamin A, was appropriately dubbed retinal. In the 1970s a microbial counterpart of this species was discovered in an archaeon, being a membrane protein also harbouring retinal as a chromophore, and named bacteriorhodopsin. Since their discovery a photogenic panorama unfolded, where up to date new members and subspecies with a variety of light-driven functionality have been added to this family. The animal branch, meanwhile categorized as type-2 rhodopsins, turned out to form a large subclass in the superfamily of G protein-coupled receptors and are essential to multiple elements of light-dependent animal sensory physiology. The microbial branch, the type-1 rhodopsins, largely function as light-driven ion pumps or channels, but also contain sensory-active and enzyme-sustaining subspecies. In this review we will follow the development of this exciting membrane protein panorama in a representative number of highlights and will present a prospect of their extraordinary future potential.
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Affiliation(s)
- Willem J. de Grip
- Leiden Institute of Chemistry, Department of Biophysical Organic Chemistry, Leiden University, Leiden, Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Srividya Ganapathy
- Department of Imaging Physics, Delft University of Technology, Netherlands
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22
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Talele S, King JT. Reaction cycle of operating pump protein studied with single-molecule spectroscopy. Chemphyschem 2022; 23:e202200099. [PMID: 35614023 DOI: 10.1002/cphc.202200099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 05/23/2022] [Indexed: 11/10/2022]
Abstract
Biological machinery relies on nonequilibrium dynamics to maintain stable directional fluxes through complex reaction cycles. For such reaction cycles, the presence of microscopically irreversible conformational transitions of the protein, and the accompanying entropy production, is of central interest. In this work, we use multidimensional single-molecule fluorescence lifetime correlation spectroscopy to measure the forward and reverse conformational transitions of bacteriorhodopsin during trans-membrane H + pumping. We quantify the flux, affinity, enthalpy and entropy production through portions of the reaction cycle as a function of temperature. We find that affinity of irreversible conformational transitions decreases with increasing temperature, resulting in diminishing flux and entropy production. We show that the temperature dependence of the transition affinity is well fit by the Gibbs-Helmholtz relation, allowing the DH trans to be experimentally extracted.
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Affiliation(s)
- Saurabh Talele
- Institute for Basic Science, Center for Soft and Living Matter, KOREA, REPUBLIC OF
| | - John Thomas King
- Institute for Basic Science, Center for Soft and Living Matter, Advanced Materials Building, Ulsan National Institute of Science and Technology, 44919, Ulsan, KOREA, REPUBLIC OF
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23
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True-atomic-resolution insights into the structure and functional role of linear chains and low-barrier hydrogen bonds in proteins. Nat Struct Mol Biol 2022; 29:440-450. [PMID: 35484235 DOI: 10.1038/s41594-022-00762-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 03/14/2022] [Indexed: 12/21/2022]
Abstract
Hydrogen bonds are fundamental to the structure and function of biological macromolecules and have been explored in detail. The chains of hydrogen bonds (CHBs) and low-barrier hydrogen bonds (LBHBs) were proposed to play essential roles in enzyme catalysis and proton transport. However, high-resolution structural data from CHBs and LBHBs is limited. The challenge is that their 'visualization' requires ultrahigh-resolution structures of the ground and functionally important intermediate states to identify proton translocation events and perform their structural assignment. Our true-atomic-resolution structures of the light-driven proton pump bacteriorhodopsin, a model in studies of proton transport, show that CHBs and LBHBs not only serve as proton pathways, but also are indispensable for long-range communications, signaling and proton storage in proteins. The complete picture of CHBs and LBHBs discloses their multifunctional roles in providing protein functions and presents a consistent picture of proton transport and storage resolving long-standing debates and controversies.
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24
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Zhong YR, Yu TY, Chu LK. Roles of functional lipids in bacteriorhodopsin photocycle in various delipidated purple membranes. Biophys J 2022; 121:1789-1798. [PMID: 35440419 DOI: 10.1016/j.bpj.2022.04.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 04/07/2022] [Accepted: 04/15/2022] [Indexed: 11/30/2022] Open
Abstract
Purple membrane (PM) is composed of several native lipids and the transmembrane protein bacteriorhodopsin (bR) in trimeric configuration. The delipidated PM (dPM) samples can be prepared by treating PM with CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) to partially remove native lipids while maintaining bR in the trimeric configuration. By correlating the photocycle kinetics of bR and the exact lipid compositions of the various dPM samples, one can reveal the roles of native PM lipids. However, it is challenging to compare the lipid compositions of the various dPM samples quantitatively. Here, we utilized the absorbances of extracted retinal at 382 nm to normalize the concentrations of the remaining lipids in each dPM sample, which were then quantified by mass spectrometry, allowing us to compare the lipid compositions of different samples in a quantitative manner. The corresponding photocycle kinetics of bR were probed by transient difference absorption spectroscopy. We found that the removal rate of the polar lipids follows the order of BPG ≈ GlyC < S-TGD-1 ≈ PG < PGP-Me ≈ PGS. Since BPG and GlyC have more nonpolar phytanyl groups than other lipids at the hydrophobic tail, causing a higher affinity with the hydrophobic surface of bR, the corresponding removal rates are slowest. In addition, as the reaction period of PM and CHAPS increases, the residual amounts of PGS and PGP-Me significantly decrease, in concomitance with the decelerated rates of the recovery of ground state and the decay of intermediate M, and the reduced transient population of intermediate O. PGS and PGP-Me are the lipids with the highest correlation to the photocycle activity among the six polar lipids of PM. From a practical viewpoint, combining optical spectroscopy and mass spectrometry appears a promising approach to simultaneously track the functions and the concomitant active components in a given biological system.
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Affiliation(s)
- Yi-Rui Zhong
- Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Rd., Hsinchu 30013, Taiwan
| | - Tsyr-Yan Yu
- Institute of Atomic and Molecular Sciences, Academia Sinica, 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan; International Graduate Program of Molecular Science and Technology, National Taiwan University, Taipei, Taiwan.
| | - Li-Kang Chu
- Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Rd., Hsinchu 30013, Taiwan.
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25
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Deng J, Cui Q. Electronic Polarization Is Essential for the Stabilization and Dynamics of Buried Ion Pairs in Staphylococcal Nuclease Mutants. J Am Chem Soc 2022; 144:4594-4610. [PMID: 35239338 PMCID: PMC9616648 DOI: 10.1021/jacs.2c00312] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Buried charged residues play important roles in the modulation of protein stabilities and conformational dynamics and make crucial contributions to protein functions. Considering the generally nonpolar nature of protein interior, a key question concerns the contribution of electronic polarization to the stabilization and properties of buried charges. We answer this question by conducting free energy simulations using the latest polarizable CHARMM force field based on Drude oscillators for a series of Staphylococcal nuclease mutants that involve a buried Glu-Lys pair in different titration states and orientations. While a nonpolarizable model suggests that the ionized form of the buried Glu-Lys pair is more than 40 kcal/mol less stable than the charge-neutral form, the two titration states are comparable in stability when electronic polarization is included explicitly, a result better reconcilable with available experimental data. Analysis of free energy components suggests that additional stabilization of the ionized Glu-Lys pair has contributions from both the enhanced salt-bridge strength and stronger interaction between the ion-pair and surrounding protein residues and penetrated water. Despite the stronger direct interaction between Glu and Lys, the ion-pair exhibits considerably larger and faster structural fluctuations when polarization is included, due to compensation of interactions in the cavity. Collectively, observations from this work provide compelling evidence that electronic polarization is essential to the stability, hydration, dynamics, and therefore function of buried charges in proteins. Therefore, our study advocates for the explicit consideration of electronic polarization for mechanistic and engineering studies that implicate buried charged residues, such as enzymes and ion transporters.
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Affiliation(s)
- Jiahua Deng
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Qiang Cui
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States.,Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States.,Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, Massachusetts 02215, United States
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26
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Suzuki K, Del Carmen Marín M, Konno M, Bagherzadeh R, Murata T, Inoue K. Structural characterization of proton-pumping rhodopsin lacking a cytoplasmic proton donor residue by X-ray crystallography. J Biol Chem 2022; 298:101722. [PMID: 35151692 PMCID: PMC8927995 DOI: 10.1016/j.jbc.2022.101722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/05/2022] [Accepted: 02/08/2022] [Indexed: 01/10/2023] Open
Abstract
DTG/DTS rhodopsin, which was named based on a three-residue motif (DTG or DTS) that is important for its function, is a light-driven proton-pumping microbial rhodopsin using a retinal chromophore. In contrast to other light-driven ion-pumping rhodopsins, DTG/DTS rhodopsin does not have a cytoplasmic proton donor residue, such as Asp, Glu, or Lys. Because of the lack of cytoplasmic proton donor residue, proton directly binds to the retinal chromophore from the cytoplasmic solvent. However, mutational experiments that showed the complicated effects of mutations were not able to clarify the roles played by each residue, and the detail of proton uptake pathway is unclear because of the lack of structural information. To understand the proton transport mechanism of DTG/DTS rhodopsin, here we report the three-dimensional structure of one of the DTG/DTS rhodopsins, PspR from Pseudomonas putida, by X-ray crystallography. We show that the structure of the cytoplasmic side of the protein is significantly different from that of bacteriorhodopsin, the best-characterized proton-pumping rhodopsin, and large cytoplasmic cavities were observed. We propose that these hydrophilic cytoplasmic cavities enable direct proton uptake from the cytoplasmic solvent without the need for a specialized cytoplasmic donor residue. The introduction of carboxylic residues homologous to the cytoplasmic donors in other proton-pumping rhodopsins resulted in higher pumping activity with less pH dependence, suggesting that DTG/DTS rhodopsins are advantageous for producing energy and avoiding intracellular alkalization in soil and plant-associated bacteria.
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Affiliation(s)
- Kano Suzuki
- Department of Chemistry, Graduate School of Science, Chiba University, Inage, Chiba, Japan
| | | | - Masae Konno
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, Japan; PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Reza Bagherzadeh
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Takeshi Murata
- Department of Chemistry, Graduate School of Science, Chiba University, Inage, Chiba, Japan; Membrane Protein Research and Molecular Chirality Research Centers, Chiba University, Inage, Chiba, Japan.
| | - Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, Japan.
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27
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Nho HW, Adhikari A, Kwon OH. Ultrafast Excited-State Proton Transfer of a Cationic Superphotoacid in a Nanoscopic Water Pool. J Phys Chem B 2022; 126:1275-1283. [PMID: 35119852 DOI: 10.1021/acs.jpcb.1c09070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The excited-state proton transfer (ESPT) of a cationic superphotoacid, N-methyl-7-hydroxyquinolium, was studied within the water pool of an anionic aerosol-OT (AOT), bis(2-ethylhexyl) sulfosuccinate, reverse micelle (RM). Previously, we had found that the cationic photoacid residing at the anionic AOT interface was conducive to ESPT to the bound water having concentric heterogeneity on the time scale of hundreds of picoseconds to nanoseconds. In our present study, on the time scale of hundreds of femtoseconds to a few tens of picoseconds, the photoacid underwent an ultrafast ESPT influenced by mobile water constituting the core of the RM. The two subpopulations of the core water molecules that determine the ultrafast biphasic deprotonation of the photoacid on time scales differing by an order of magnitude were identified. The core water molecules solvating the counteranion of the photoacid showed a higher basicity than typical water clusters in bulk resulting in ESPT on a subpicosecond time scale. Bare water clusters sensed by the photoacid showed a slower ESPT, over several picoseconds, as typically limited by the rotational motion of water molecules for similar types of the photoacid.
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Affiliation(s)
- Hak-Won Nho
- Department of Chemistry, College of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.,Center for Soft and Living Matter, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Aniruddha Adhikari
- Department of Chemistry, College of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Oh-Hoon Kwon
- Department of Chemistry, College of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.,Center for Soft and Living Matter, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
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28
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Bondar AN. Mechanisms of long-distance allosteric couplings in proton-binding membrane transporters. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 128:199-239. [PMID: 35034719 DOI: 10.1016/bs.apcsb.2021.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Membrane transporters that use proton binding and proton transfer for function couple local protonation change with changes in protein conformation and water dynamics. Changes of protein conformation might be required to allow transient formation of hydrogen-bond networks that bridge proton donor and acceptor pairs separated by long distances. Inter-helical hydrogen-bond networks adjust rapidly to protonation change, and ensure rapid response of the protein structure and dynamics. Membrane transporters with known three-dimensional structures and proton-binding groups inform on general principles of protonation-coupled protein conformational dynamics. Inter-helical hydrogen bond motifs between proton-binding carboxylate groups and a polar sidechain are observed in unrelated membrane transporters, suggesting common principles of coupling protonation change with protein conformational dynamics.
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Affiliation(s)
- Ana-Nicoleta Bondar
- University of Bucharest, Faculty of Physics, Măgurele, Romania; Forschungszentrum Jülich, Institute of Computational Biomedicine, Jülich, Germany.
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29
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Hornemann A, Eichert DM, Hoehl A, Tiersch B, Ulm G, Ryadnov MG, Beckhoff B. Investigating Membrane‐Mediated Antimicrobial Peptide Interactions with Synchrotron Radiation Far‐Infrared Spectroscopy. Chemphyschem 2022; 23:e202100815. [PMID: 35032089 PMCID: PMC9303692 DOI: 10.1002/cphc.202100815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/20/2021] [Indexed: 11/30/2022]
Abstract
Synchrotron radiation‐based Fourier transform infrared spectroscopy enables access to vibrational information from mid over far infrared to even terahertz domains. This information may prove critical for the elucidation of fundamental bio‐molecular phenomena including folding‐mediated innate host defence mechanisms. Antimicrobial peptides (AMPs) represent one of such phenomena. These are major effector molecules of the innate immune system, which favour attack on microbial membranes. AMPs recognise and bind to the membranes whereupon they assemble into pores or channels destabilising the membranes leading to cell death. However, specific molecular interactions responsible for antimicrobial activities have yet to be fully understood. Herein we probe such interactions by assessing molecular specific variations in the near‐THz 400–40 cm−1 range for defined helical AMP templates in reconstituted phospholipid membranes. In particular, we show that a temperature‐dependent spectroscopic analysis, supported by 2D correlative tools, provides direct evidence for the membrane‐induced and folding‐mediated activity of AMPs. The far‐FTIR study offers a direct and information‐rich probe of membrane‐related antimicrobial interactions.
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Affiliation(s)
- Andrea Hornemann
- Department 7.1 Radiometry with Synchrotron Radiation and Department 7.2 X-Ray Metrology with Synchrotron Radiation Physikalisch-Technische Bundesanstalt (PTB) Abbestr. 2–12 10587 Berlin Germany
| | - Diane M. Eichert
- ELETTRA – Sincrotrone Trieste S.S.14 Km 163.5 in Area Science Park 34149 Basovizza Trieste Italy
| | - Arne Hoehl
- Department 7.1 Radiometry with Synchrotron Radiation and Department 7.2 X-Ray Metrology with Synchrotron Radiation Physikalisch-Technische Bundesanstalt (PTB) Abbestr. 2–12 10587 Berlin Germany
| | - Brigitte Tiersch
- Universität Potsdam Karl-Liebknecht-Str. 24–25 14476 Potsdam Germany
| | - Gerhard Ulm
- Department 7.1 Radiometry with Synchrotron Radiation and Department 7.2 X-Ray Metrology with Synchrotron Radiation Physikalisch-Technische Bundesanstalt (PTB) Abbestr. 2–12 10587 Berlin Germany
| | - Maxim G. Ryadnov
- National Physical Laboratory Hampton Rd Teddington Middlesex TW11 0LW UK
| | - Burkhard Beckhoff
- Department 7.1 Radiometry with Synchrotron Radiation and Department 7.2 X-Ray Metrology with Synchrotron Radiation Physikalisch-Technische Bundesanstalt (PTB) Abbestr. 2–12 10587 Berlin Germany
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30
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Phenanthroline-based Ni(II) coordination compounds involving unconventional discrete fumarate-water-nitrate clusters and energetically significant cooperative ternary π-stacked assemblies: Antiproliferative evaluation and theoretical studies. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2021.131424] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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31
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Großerueschkamp F, Jütte H, Gerwert K, Tannapfel A. Advances in Digital Pathology: From Artificial Intelligence to Label-Free Imaging. Visc Med 2021; 37:482-490. [PMID: 35087898 DOI: 10.1159/000518494] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/14/2021] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Digital pathology, in its primary meaning, describes the utilization of computer screens to view scanned histology slides. Digitized tissue sections can be easily shared for a second opinion. In addition, it allows tissue image analysis using specialized software to identify and measure events previously observed by a human observer. These tissue-based readouts were highly reproducible and precise. Digital pathology has developed over the years through new technologies. Currently, the most discussed development is the application of artificial intelligence to automatically analyze tissue images. However, even new label-free imaging technologies are being developed to allow imaging of tissues by means of their molecular composition. SUMMARY This review provides a summary of the current state-of-the-art and future digital pathologies. Developments in the last few years have been presented and discussed. In particular, the review provides an outlook on interesting new technologies (e.g., infrared imaging), which would allow for deeper understanding and analysis of tissue thin sections beyond conventional histopathology. KEY MESSAGES In digital pathology, mathematical methods are used to analyze images and draw conclusions about diseases and their progression. New innovative methods and techniques (e.g., label-free infrared imaging) will bring significant changes in the field in the coming years.
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Affiliation(s)
- Frederik Großerueschkamp
- Center for Protein Diagnostics (PRODI), Biospectroscopy, Ruhr University Bochum, Bochum, Germany.,Department of Biophysics, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Hendrik Jütte
- Center for Protein Diagnostics (PRODI), Biospectroscopy, Ruhr University Bochum, Bochum, Germany.,Institute of Pathology, Ruhr University Bochum, Bochum, Germany
| | - Klaus Gerwert
- Center for Protein Diagnostics (PRODI), Biospectroscopy, Ruhr University Bochum, Bochum, Germany.,Department of Biophysics, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Andrea Tannapfel
- Center for Protein Diagnostics (PRODI), Biospectroscopy, Ruhr University Bochum, Bochum, Germany.,Institute of Pathology, Ruhr University Bochum, Bochum, Germany
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32
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Zhu X, Chen Y, Xie R, Zhong H, Zhao W, Liu Y, Yang H. Rapid Gelling of Guar Gum Hydrogel Stabilized by Copper Hydroxide Nanoclusters for Efficient Removal of Heavy Metal and Supercapacitors. Front Chem 2021; 9:794755. [PMID: 34869238 PMCID: PMC8637109 DOI: 10.3389/fchem.2021.794755] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 10/31/2021] [Indexed: 11/29/2022] Open
Abstract
In this paper, guar gum (GG) hydrogel has been successfully prepared by adding GG and Cu2+ mixture into an alkaline medium. The formation mechanism of the hydrogel has been investigated through various techniques. Results reveal GG facilitates the formation of ultrafine copper hydroxide clusters with a diameter of ∼3 nm. Moreover, these nanoclusters bring about a rapid gelling of GG within 10 ms. The synthesized hydrogel is applied to the adsorption of heavy metal ions from wastewater. The hydrogel shows excellent removal efficiency in removing various heavy metal ions. Besides, the hydrogel derived porous carbon exhibits high specific capacitance (281 F/g at 1 A/g) and excellent rate capacity. The high contaminant removal efficiency character and excellent electrochemical performance endow GG hydrogel with potential applications in the environmental and energy storage field.
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Affiliation(s)
- Xinwei Zhu
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China
- Key Laboratory of Biomaterials and Bio-fabrication in Tissue Engineering of Jiangxi Province, Ganzhou, China
- School of Rehabilitation Medicine, Gannan Medical University, Ganzhou, China
| | - Yingxi Chen
- First Affiliated Hospital of Gannan Medical University, Ganzhou, China
| | - Renjian Xie
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China
- Key Laboratory of Biomaterials and Bio-fabrication in Tissue Engineering of Jiangxi Province, Ganzhou, China
- School of Medical Information Engineering, Gannan Medical University, Ganzhou, China
| | - Haijian Zhong
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China
- Key Laboratory of Biomaterials and Bio-fabrication in Tissue Engineering of Jiangxi Province, Ganzhou, China
- School of Medical Information Engineering, Gannan Medical University, Ganzhou, China
| | - Weidong Zhao
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China
- Key Laboratory of Biomaterials and Bio-fabrication in Tissue Engineering of Jiangxi Province, Ganzhou, China
- School of Medical Information Engineering, Gannan Medical University, Ganzhou, China
| | - Yang Liu
- Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, China
| | - Hui Yang
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China
- Key Laboratory of Biomaterials and Bio-fabrication in Tissue Engineering of Jiangxi Province, Ganzhou, China
- School of Medical Information Engineering, Gannan Medical University, Ganzhou, China
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33
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Ohmine I, Saito S. Dynamical Behavior of Water; Fluctuation, Reactions and Phase Transitions. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20210269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Iwao Ohmine
- Institute for Molecular Science, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Shinji Saito
- Institute for Molecular Science, Myodaiji, Okazaki, Aichi 444-8585, Japan
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34
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Nakai H, Takemura T, Ono J, Nishimura Y. Quantum-Mechanical Molecular Dynamics Simulations on Secondary Proton Transfer in Bacteriorhodopsin Using Realistic Models. J Phys Chem B 2021; 125:10947-10963. [PMID: 34582194 DOI: 10.1021/acs.jpcb.1c06231] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Bacteriorhodopsin (BR) transports a proton from intracellular to extracellular (EC) sites through five proton transfers. The second proton transfer is the release of an excess proton stored in BR into the EC medium, and an atomistic understanding of this whole process has remained unexplored due to its ubiquitous environment. Here, fully quantum mechanical (QM) molecular dynamics (MD) and metadynamics (MTD) simulations for this process were performed at the divide-and-conquer density-functional tight-binding level using realistic models (∼50000 and ∼20000 atoms) based on the time-resolved photointermediate structures from an X-ray free electron laser. Regarding the proton storage process, the QM-MD/MTD simulations confirmed the Glu-shared mechanism, in which an excess proton is stored between Glu194 and Glu204, and clarified that the activation occurs by localizing the proton at Glu204 in the photocycle. Furthermore, the QM-MD/MTD simulations elucidated a release pathway from Glu204 through Ser193 to the EC water molecules and clarified that the proton release starts at ∼250 μs. In the ubiquitous proton diffusion in the EC medium, the transient proton receptors predicted experimentally were assigned to carboxylates in Glu9 and Glu74. Large-scale QM-MD/MTD simulations beyond the conventional sizes, which provided the above findings and confirmations, were possible by adopting our Dcdftbmd program.
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Affiliation(s)
- Hiromi Nakai
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.,Waseda Research Institute for Science and Engineering (WISE), Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.,Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, 1-30 Goryo-Ohara, Nishikyo-ku, Kyoto 615-8245, Japan
| | - Toshiaki Takemura
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan
| | - Junichi Ono
- Waseda Research Institute for Science and Engineering (WISE), Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan.,Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, 1-30 Goryo-Ohara, Nishikyo-ku, Kyoto 615-8245, Japan
| | - Yoshifumi Nishimura
- Waseda Research Institute for Science and Engineering (WISE), Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan
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35
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Sharma G, Merz KM. Formation of the Metal-Binding Core of the ZRT/IRT-like Protein (ZIP) Family Zinc Transporter. Biochemistry 2021; 60:2727-2738. [PMID: 34455776 DOI: 10.1021/acs.biochem.1c00415] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Zinc homeostasis in mammals is constantly and precisely maintained by sophisticated regulatory proteins. Among them, the Zrt/Irt-like protein (ZIP) regulates the influx of zinc into the cytoplasm. In this work, we have employed all-atom molecular dynamics simulations to investigate the Zn2+ transport mechanism in prokaryotic ZIP obtained from Bordetella bronchiseptica (BbZIP) in a membrane bilayer. Additionally, the structural and dynamical transformations of BbZIP during this process have been analyzed. This study allowed us to develop a hypothesis for the zinc influx mechanism and formation of the metal-binding site. We have created a model for the outward-facing form of BbZIP (experimentally only the inward-facing form has been characterized) that has allowed us, for the first time, to observe the Zn2+ ion entering the channel and binding to the negatively charged M2 site. It is thought that the M2 site is less favored than the M1 site, which then leads to metal ion egress; however, we have not observed the M1 site being occupied in our simulations. Furthermore, removing both Zn2+ ions from this complex resulted in the collapse of the metal-binding site, illustrating the "structural role" of metal ions in maintaining the binding site and holding the proteins together. Finally, due to the long Cd2+-residue bond distances observed in the X-ray structures, we have proposed the existence of an H3O+ ion at the M2 site that plays an important role in protein stability in the absence of the metal ion.
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Affiliation(s)
- Gaurav Sharma
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Kenneth M Merz
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States.,Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, United States
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36
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Yagi K, Sugita Y. Anharmonic Vibrational Calculations Based on Group-Localized Coordinates: Applications to Internal Water Molecules in Bacteriorhodopsin. J Chem Theory Comput 2021; 17:5007-5020. [PMID: 34296615 PMCID: PMC10986902 DOI: 10.1021/acs.jctc.1c00060] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
An efficient anharmonic vibrational method is developed exploiting the locality of molecular vibration. Vibrational coordinates localized to a group of atoms are employed to divide the potential energy surface (PES) of a system into intra- and inter-group contributions. Then, the vibrational Schrödinger equation is solved based on a PES, in which the inter-group coupling is truncated at the harmonic level while accounting for the intra-group anharmonicity. The method is applied to a pentagonal hydrogen bond network (HBN) composed of internal water molecules and charged residues in a membrane protein, bacteriorhodopsin. The PES is calculated by the quantum mechanics/molecular mechanics (QM/MM) calculation at the level of B3LYP-D3/aug-cc-pVDZ. The infrared (IR) spectrum is computed using a set of coordinates localized to each water molecule and amino acid residue by second-order vibrational quasi-degenerate perturbation theory (VQDPT2). Benchmark calculations show that the proposed method yields the N-D/O-D stretching frequencies with an error of 7 cm-1 at the cost reduced by more than five times. In contrast, the harmonic approximation results in a severe error of 150 cm-1. Furthermore, the size of QM regions is carefully assessed to find that the QM regions should include not only the pentagonal HBN itself but also its HB partners. VQDPT2 calculations starting from transient structures obtained by molecular dynamics simulations have shown that the structural sampling has a significant impact on the calculated IR spectrum. The incorporation of anharmonicity, sufficiently large QM regions, and structural samplings are of essential importance to reproduce the experimental IR spectrum. The computational spectrum paves the way for decoding the IR signal of strong HBNs and helps elucidate their functional roles in biomolecules.
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Affiliation(s)
- Kiyoshi Yagi
- Theoretical
Molecular Science Laboratory, RIKEN Cluster
for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Yuji Sugita
- Theoretical
Molecular Science Laboratory, RIKEN Cluster
for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Computational
Biophysics Research Team, RIKEN Center for
Computational Science, 7-1-26 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
- Laboratory
for Biomolecular Function Simulation, RIKEN
Center for Biosystems Dynamics Research, 1-6-5 Minatojima-Minamimachi,
Chuo-ku, Kobe, Hyogo 650-0047, Japan
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37
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Kurzydłowski D, Chumak T, Rogoża J, Listkowski A. Hydrogen-Bonded Cyclic Dimers at Large Compression: The Case of 1 H-pyrrolo[3,2- h]quinoline and 2-(2'-pyridyl)pyrrole. Molecules 2021; 26:molecules26133802. [PMID: 34206494 PMCID: PMC8270273 DOI: 10.3390/molecules26133802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/18/2021] [Accepted: 06/19/2021] [Indexed: 11/17/2022] Open
Abstract
1H-pyrrolo[3,2-h]qinoline (PQ) and 2-(2′-pyridyl)pyrrole (PP) are important systems in the study of proton-transfer reactions. These molecules possess hydrogen bond donor (pyrrole) and acceptor (pyridine) groups, which leads to the formation of cyclic dimers in their crystals. Herein, we present a joint experimental (Raman scattering) and computational (DFT modelling) study on the high-pressure behaviour of PQ and PP molecular crystals. Our results indicate that compression up to 10 GPa (100 kbar) leads to considerable strengthening of the intermolecular hydrogen bond within the cyclic dimers. However, the intramolecular N–H∙∙∙N interaction is either weakly affected by pressure, as witnessed in PQ, or weakened due to compression-induced distortions of the molecule, as was found for PP. Therefore, we propose that the compression of these systems should facilitate double proton transfer within the cyclic dimers of PQ and PP, while intramolecular transfer should either remain unaffected (for PQ) or weakened (for PP).
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Affiliation(s)
- Dominik Kurzydłowski
- Faculty of Mathematics and Natural Sciences, Cardinal Stefan Wyszyński University, 01-038 Warsaw, Poland; (T.C.); (A.L.)
- Correspondence:
| | - Taisiia Chumak
- Faculty of Mathematics and Natural Sciences, Cardinal Stefan Wyszyński University, 01-038 Warsaw, Poland; (T.C.); (A.L.)
| | - Jakub Rogoża
- Faculty of Physics, University of Warsaw, 02-093 Warsaw, Poland;
| | - Arkadiusz Listkowski
- Faculty of Mathematics and Natural Sciences, Cardinal Stefan Wyszyński University, 01-038 Warsaw, Poland; (T.C.); (A.L.)
- Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland
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38
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Affiliation(s)
- Sven T. Stripp
- Freie Universität Berlin, Department of Physics, Arnimallee 14, 14195 Berlin, Germany
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39
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Ultrafast proton release reaction and primary photochemistry of phycocyanobilin in solution observed with fs-time-resolved mid-IR and UV/Vis spectroscopy. Photochem Photobiol Sci 2021; 20:715-732. [PMID: 34002345 DOI: 10.1007/s43630-021-00045-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 04/16/2021] [Indexed: 12/27/2022]
Abstract
Deactivation processes of photoexcited (λex = 580 nm) phycocyanobilin (PCB) in methanol were investigated by means of UV/Vis and mid-IR femtosecond (fs) transient absorption (TA) as well as static fluorescence spectroscopy, supported by density-functional-theory calculations of three relevant ground state conformers, PCBA, PCBB and PCBC, their relative electronic state energies and normal mode vibrational analysis. UV/Vis fs-TA reveals time constants of 2.0, 18 and 67 ps, describing decay of PCBB*, of PCBA* and thermal re-equilibration of PCBA, PCBB and PCBC, respectively, in line with the model by Dietzek et al. (Chem Phys Lett 515:163, 2011) and predecessors. Significant substantiation and extension of this model is achieved first via mid-IR fs-TA, i.e. identification of molecular structures and their dynamics, with time constants of 2.6, 21 and 40 ps, respectively. Second, transient IR continuum absorption (CA) is observed in the region above 1755 cm-1 (CA1) and between 1550 and 1450 cm-1 (CA2), indicative for the IR absorption of highly polarizable protons in hydrogen bonding networks (X-H…Y). This allows to characterize chromophore protonation/deprotonation processes, associated with the electronic and structural dynamics, on a molecular level. The PCB photocycle is suggested to be closed via a long living (> 1 ns), PCBC-like (i.e. deprotonated), fluorescent species.
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40
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Dreier MA, Althoff P, Norahan MJ, Tennigkeit SA, El-Mashtoly SF, Lübben M, Kötting C, Rudack T, Gerwert K. Time-resolved spectroscopic and electrophysiological data reveal insights in the gating mechanism of anion channelrhodopsin. Commun Biol 2021; 4:578. [PMID: 33990694 PMCID: PMC8121809 DOI: 10.1038/s42003-021-02101-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 04/12/2021] [Indexed: 02/04/2023] Open
Abstract
Channelrhodopsins are widely used in optogenetic applications. High photocurrents and low current inactivation levels are desirable. Two parallel photocycles evoked by different retinal conformations cause cation-conducting channelrhodopsin-2 (CrChR2) inactivation: one with efficient conductivity; one with low conductivity. Given the longer half-life of the low conducting photocycle intermediates, which accumulate under continuous illumination, resulting in a largely reduced photocurrent. Here, we demonstrate that for channelrhodopsin-1 of the cryptophyte Guillardia theta (GtACR1), the highly conducting C = N-anti-photocycle was the sole operating cycle using time-resolved step-scan FTIR spectroscopy. The correlation between our spectroscopic measurements and previously reported electrophysiological data provides insights into molecular gating mechanisms and their role in the characteristic high photocurrents. The mechanistic importance of the central constriction site amino acid Glu-68 is also shown. We propose that canceling out the poorly conducting photocycle avoids the inactivation observed in CrChR2, and anticipate that this discovery will advance the development of optimized optogenetic tools.
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Affiliation(s)
- Max-Aylmer Dreier
- Biospectroscopy, Center for Protein Diagnostics (PRODI), Ruhr University Bochum, Bochum, Germany
- Department of Biophysics, Ruhr University Bochum, Bochum, Germany
| | - Philipp Althoff
- Biospectroscopy, Center for Protein Diagnostics (PRODI), Ruhr University Bochum, Bochum, Germany
- Department of Biophysics, Ruhr University Bochum, Bochum, Germany
| | - Mohamad Javad Norahan
- Biospectroscopy, Center for Protein Diagnostics (PRODI), Ruhr University Bochum, Bochum, Germany
- Department of Biophysics, Ruhr University Bochum, Bochum, Germany
| | - Stefan Alexander Tennigkeit
- Biospectroscopy, Center for Protein Diagnostics (PRODI), Ruhr University Bochum, Bochum, Germany
- Department of Biophysics, Ruhr University Bochum, Bochum, Germany
| | - Samir F El-Mashtoly
- Biospectroscopy, Center for Protein Diagnostics (PRODI), Ruhr University Bochum, Bochum, Germany
- Department of Biophysics, Ruhr University Bochum, Bochum, Germany
| | - Mathias Lübben
- Biospectroscopy, Center for Protein Diagnostics (PRODI), Ruhr University Bochum, Bochum, Germany
- Department of Biophysics, Ruhr University Bochum, Bochum, Germany
| | - Carsten Kötting
- Biospectroscopy, Center for Protein Diagnostics (PRODI), Ruhr University Bochum, Bochum, Germany
- Department of Biophysics, Ruhr University Bochum, Bochum, Germany
| | - Till Rudack
- Biospectroscopy, Center for Protein Diagnostics (PRODI), Ruhr University Bochum, Bochum, Germany.
- Department of Biophysics, Ruhr University Bochum, Bochum, Germany.
| | - Klaus Gerwert
- Biospectroscopy, Center for Protein Diagnostics (PRODI), Ruhr University Bochum, Bochum, Germany.
- Department of Biophysics, Ruhr University Bochum, Bochum, Germany.
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41
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Zeng HJ, Johnson MA. Demystifying the Diffuse Vibrational Spectrum of Aqueous Protons Through Cold Cluster Spectroscopy. Annu Rev Phys Chem 2021; 72:667-691. [PMID: 33646816 DOI: 10.1146/annurev-physchem-061020-053456] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ease with which the pH is routinely determined for aqueous solutions masks the fact that the cationic product of Arrhenius acid dissolution, the hydrated proton, or H+(aq), is a remarkably complex species. Here, we review how results obtained over the past 30 years in the study of H+⋅(H2O)n cluster ions isolated in the gas phase shed light on the chemical nature of H+(aq). This effort has also revealed molecular-level aspects of the Grotthuss relay mechanism for positive-charge translocation in water. Recently developed methods involving cryogenic cooling in radiofrequency ion traps and the application of two-color, infrared-infrared (IR-IR) double-resonance spectroscopy have established a clear picture of how local hydrogen-bond topology drives the diverse spectral signatures of the excess proton. This information now enables a new generation of cluster studies designed to unravel the microscopic mechanics underlying the ultrafast relaxation dynamics displayed by H+(aq).
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Affiliation(s)
- Helen J Zeng
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, USA;
| | - Mark A Johnson
- Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520, USA;
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42
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Klein D, Breuch R, Reinmüller J, Engelhard C, Kaul P. Rapid detection and discrimination of food-related bacteria using IR-microspectroscopy in combination with multivariate statistical analysis. Talanta 2021; 232:122424. [PMID: 34074410 DOI: 10.1016/j.talanta.2021.122424] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 03/30/2021] [Accepted: 04/09/2021] [Indexed: 10/21/2022]
Abstract
Spoilage microorganisms are of great concern for the food industry. While traditional culturing methods for spoilage microorganism detection are laborious and time-consuming, the development of early detection methods has gained a lot of interest in the last decades. In this work a rapid and non-destructive detection and discrimination method of eight important food-related microorganisms (Bacillus subtilis DSM 10, Bacillus coagulans DSM 1, Escherichia coli K12 DSM 498, Escherichia coli TOP10, Micrococcus luteus DSM 20030, Pseudomonas fluorescens DSM 4358, Pseudomonas fluorescens DSM 50090 and Bacillus thuringiensis israelensis DSM 5724) based on IR-microspectroscopy and chemometric evaluation was developed. Sampling was carried out directly from the surface to be tested, without the need for sample preparation such as purification, singulation, centrifugation and washing steps, as an efficient and inexpensive blotting technique using the sample carrier. IR spectra were recorded directly after the blotting from the surface of the sample carrier without any further pretreatments. A combination of data preprocessing, principal component analysis and canonical discriminant analysis was found to be suitable. The spectral range from 400 to 1750 cm-1 of the IR-microspectrosopic data was determined to be highly sensitive to the time after incubation and sample thickness, resulting in a high standard deviation. Therefore, this area was excluded from the evaluation in favor of the meaningfulness of the chemometric model and, thus, only the spectral range of specific -CH/-NH/-OH excitations (2815-3680 cm-1) was used for model development. This study showed that the differentiation of food-related microorganisms on genera, species and strain level is feasible. A leave-one-out cross-validation of the training data set showed 100% accuracy. The classification of the ungrouped test data showed with an accuracy of 94.5% that, despite the large biological variance of the analytes such as different times after incubation and the presented sampling (including its variance), a robust and meaningful model for the differentiation of food-related bacteria could be developed by data preprocessing and subsequent chemometric evaluation.
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Affiliation(s)
- Daniel Klein
- Bonn-Rhein-Sieg University of Applied Sciences, Institute of Safety and Security Research, von Liebig-Straße 20, 53359, Rheinbach, Germany.
| | - René Breuch
- Bonn-Rhein-Sieg University of Applied Sciences, Institute of Safety and Security Research, von Liebig-Straße 20, 53359, Rheinbach, Germany
| | - Jessica Reinmüller
- Bonn-Rhein-Sieg University of Applied Sciences, Institute of Safety and Security Research, von Liebig-Straße 20, 53359, Rheinbach, Germany
| | - Carsten Engelhard
- Department of Chemistry and Biology, University of Siegen, Adolf-Reichwein-Str. 2, D-57076, Germany; Center of Micro- and Nanochemistry and Engineering, University of Siegen, Adolf-Reichwein-Str. 2, D-57076, Siegen, Germany
| | - Peter Kaul
- Bonn-Rhein-Sieg University of Applied Sciences, Institute of Safety and Security Research, von Liebig-Straße 20, 53359, Rheinbach, Germany
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43
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Abstract
Schizorhodopsins (SzRs), a new rhodopsin family identified in Asgard archaea, are phylogenetically located at an intermediate position between type-1 microbial rhodopsins and heliorhodopsins. SzRs work as light-driven inward H+ pumps as xenorhodopsins in bacteria. Although E81 plays an essential role in inward H+ release, the H+ is not metastably trapped in such a putative H+ acceptor, unlike the other H+ pumps. It remains elusive why SzR exhibits different kinetic behaviors in H+ release. Here, we report the crystal structure of SzR AM_5_00977 at 2.1 Å resolution. The SzR structure superimposes well on that of bacteriorhodopsin rather than heliorhodopsin, suggesting that SzRs are classified with type-1 rhodopsins. The structure-based mutagenesis study demonstrated that the residues N100 and V103 around the β-ionone ring are essential for color tuning in SzRs. The cytoplasmic parts of transmembrane helices 2, 6, and 7 are shorter than those in the other microbial rhodopsins, and thus E81 is located near the cytosol and easily exposed to the solvent by light-induced structural change. We propose a model of untrapped inward H+ release; H+ is released through the water-mediated transport network from the retinal Schiff base to the cytosol by the side of E81. Moreover, most residues on the H+ transport pathway are not conserved between SzRs and xenorhodopsins, suggesting that they have entirely different inward H+ release mechanisms.
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Schriever K, Saenz-Mendez P, Rudraraju RS, Hendrikse NM, Hudson EP, Biundo A, Schnell R, Syrén PO. Engineering of Ancestors as a Tool to Elucidate Structure, Mechanism, and Specificity of Extant Terpene Cyclase. J Am Chem Soc 2021; 143:3794-3807. [PMID: 33496585 PMCID: PMC8023661 DOI: 10.1021/jacs.0c10214] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Indexed: 12/21/2022]
Abstract
Structural information is crucial for understanding catalytic mechanisms and to guide enzyme engineering efforts of biocatalysts, such as terpene cyclases. However, low sequence similarity can impede homology modeling, and inherent protein instability presents challenges for structural studies. We hypothesized that X-ray crystallography of engineered thermostable ancestral enzymes can enable access to reliable homology models of extant biocatalysts. We have applied this concept in concert with molecular modeling and enzymatic assays to understand the structure activity relationship of spiroviolene synthase, a class I terpene cyclase, aiming to engineer its specificity. Engineering a surface patch in the reconstructed ancestor afforded a template structure for generation of a high-confidence homology model of the extant enzyme. On the basis of structural considerations, we designed and crystallized ancestral variants with single residue exchanges that exhibited tailored substrate specificity and preserved thermostability. We show how the two single amino acid alterations identified in the ancestral scaffold can be transferred to the extant enzyme, conferring a specificity switch that impacts the extant enzyme's specificity for formation of the diterpene spiroviolene over formation of sesquiterpenes hedycaryol and farnesol by up to 25-fold. This study emphasizes the value of ancestral sequence reconstruction combined with enzyme engineering as a versatile tool in chemical biology.
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Affiliation(s)
- Karen Schriever
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Science
for Life Laboratory, KTH Royal Institute
of Technology, 114 28 Stockholm, Sweden
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Department
of Fibre and Polymer Technology, KTH Royal
Institute of Technology, 114 28 Stockholm, Sweden
| | - Patricia Saenz-Mendez
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Science
for Life Laboratory, KTH Royal Institute
of Technology, 114 28 Stockholm, Sweden
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Department
of Fibre and Polymer Technology, KTH Royal
Institute of Technology, 114 28 Stockholm, Sweden
| | | | - Natalie M. Hendrikse
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Science
for Life Laboratory, KTH Royal Institute
of Technology, 114 28 Stockholm, Sweden
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Department
of Fibre and Polymer Technology, KTH Royal
Institute of Technology, 114 28 Stockholm, Sweden
- Swedish
Orphan Biovitrum AB, 112
76 Stockholm, Sweden
| | - Elton P. Hudson
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Science
for Life Laboratory, KTH Royal Institute
of Technology, 114 28 Stockholm, Sweden
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Department
of Protein Science, KTH Royal Institute
of Technology, 114 28 Stockholm, Sweden
| | - Antonino Biundo
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Science
for Life Laboratory, KTH Royal Institute
of Technology, 114 28 Stockholm, Sweden
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Department
of Fibre and Polymer Technology, KTH Royal
Institute of Technology, 114 28 Stockholm, Sweden
| | - Robert Schnell
- Department
of Medical Biochemistry and Biophysics, Karolinska Institutet, 17 165 Stockholm, Sweden
| | - Per-Olof Syrén
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Science
for Life Laboratory, KTH Royal Institute
of Technology, 114 28 Stockholm, Sweden
- School
of Engineering Sciences in Chemistry, Biotechnology and Health, Department
of Fibre and Polymer Technology, KTH Royal
Institute of Technology, 114 28 Stockholm, Sweden
- Wallenberg
Wood Science Center, Teknikringen 56−58, 100 44 Stockholm, Sweden
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Goett-Zink L, Klocke JL, Kottke T. Resolving Structural Changes of Photoreceptors in Living Escherichia coli via In-cell Infrared Difference Spectroscopy. Bio Protoc 2021; 11:e3909. [PMID: 33732796 DOI: 10.21769/bioprotoc.3909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 11/12/2020] [Accepted: 11/18/2020] [Indexed: 11/02/2022] Open
Abstract
Several in-cell spectroscopic techniques have been developed recently to investigate the structure and mechanism of proteins in their native environment. Conditions in vivo differ dramatically from those selected for in vitro experiments. Accordingly, the cellular environment can affect the protein mechanism for example by molecular crowding or binding of small molecules. Fourier transform infrared (FTIR) difference spectroscopy is a well-suited method to study the light-induced structural responses of photoreceptors including changes in cofactor, side chains and secondary structure. Here, we describe a protocol to study the response of cofactor and protein in living E. coli cells via in-cell infrared difference (ICIRD) spectroscopy using the attenuated total reflection (ATR) configuration. Proteins are overexpressed in E. coli, the cells are transferred into saline solution and the copy number per cell is determined using fluorescence spectroscopy. The suspension is centrifuged and the concentrated cells transferred onto the ATR cell inside the FTIR spectrometer. The thermostatted cell is sealed and illuminated from the top with an LED. Intensity spectra are recorded before and after illumination to generate the difference spectrum of the receptor inside the living cell. With ICIRD spectroscopy, structural changes of soluble photoreceptors are resolved in a near-native environment. The approach works in H2O at ambient conditions, is label free, without any limitations in protein size and does not require any purification step. Graphic abstract: In-cell infrared difference spectroscopy on photoreceptors in living E. coli using attenuated total reflection.
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Affiliation(s)
- Lukas Goett-Zink
- Department of Chemistry, Bielefeld University, Bielefeld, Germany
| | - Jessica L Klocke
- Department of Chemistry, Bielefeld University, Bielefeld, Germany
| | - Tilman Kottke
- Department of Chemistry, Bielefeld University, Bielefeld, Germany.,Medical School OWL, Bielefeld University, Bielefeld, Germany
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46
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Rao S, Klesse G, Lynch CI, Tucker SJ, Sansom MSP. Molecular Simulations of Hydrophobic Gating of Pentameric Ligand Gated Ion Channels: Insights into Water and Ions. J Phys Chem B 2021; 125:981-994. [PMID: 33439645 PMCID: PMC7869105 DOI: 10.1021/acs.jpcb.0c09285] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/13/2020] [Indexed: 12/30/2022]
Abstract
Ion channels are proteins which form gated nanopores in biological membranes. Many channels exhibit hydrophobic gating, whereby functional closure of a pore occurs by local dewetting. The pentameric ligand gated ion channels (pLGICs) provide a biologically important example of hydrophobic gating. Molecular simulation studies comparing additive vs polarizable models indicate predictions of hydrophobic gating are robust to the model employed. However, polarizable models suggest favorable interactions of hydrophobic pore-lining regions with chloride ions, of relevance to both synthetic carriers and channel proteins. Electrowetting of a closed pLGIC hydrophobic gate requires too high a voltage to occur physiologically but may inform designs for switchable nanopores. Global analysis of ∼200 channels yields a simple heuristic for structure-based prediction of (closed) hydrophobic gates. Simulation-based analysis is shown to provide an aid to interpretation of functional states of new channel structures. These studies indicate the importance of understanding the behavior of water and ions within the nanoconfined environment presented by ion channels.
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Affiliation(s)
- Shanlin Rao
- Department
of Biochemistry, University of Oxford, Oxford, U.K.
| | - Gianni Klesse
- Clarendon
Laboratory, Department of Physics, University
of Oxford, Oxford, U.K.
| | | | - Stephen J. Tucker
- Clarendon
Laboratory, Department of Physics, University
of Oxford, Oxford, U.K.
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47
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He H, Zhang L, Yue S, Yu S, Wei J, Ouyang J. Enhancement in the Mechanical Stretchability of PEDOT:PSS Films by Compounds of Multiple Hydroxyl Groups for Their Application as Transparent Stretchable Conductors. Macromolecules 2021. [DOI: 10.1021/acs.macromol.0c02309] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Hao He
- Department of Materials Science & Engineering, National University of Singapore, Singapore 117579, Singapore
| | - Lei Zhang
- Department of Materials Science & Engineering, National University of Singapore, Singapore 117579, Singapore
| | - Shizhong Yue
- Department of Materials Science & Engineering, National University of Singapore, Singapore 117579, Singapore
| | - Suzhu Yu
- Singapore Institute of Manufacturing Technology, 73 Nanyang Drive, Singapore 637662, Singapore
| | - Jun Wei
- Harbin Institute of Technology, University Town of Shenzhen, HIT Campus, Nanshan District, Shenzhen 518055, P. R. China
| | - Jianyong Ouyang
- Department of Materials Science & Engineering, National University of Singapore, Singapore 117579, Singapore
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48
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Inoue K. Diversity, Mechanism, and Optogenetic Application of Light-Driven Ion Pump Rhodopsins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1293:89-126. [PMID: 33398809 DOI: 10.1007/978-981-15-8763-4_6] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Ion-transporting microbial rhodopsins are widely used as major molecular tools in optogenetics. They are categorized into light-gated ion channels and light-driven ion pumps. While the former passively transport various types of cations and anions in a light-dependent manner, light-driven ion pumps actively transport specific ions, such as H+, Na+, Cl-, against electrophysiological potential by using light energy. Since the ion transport by these pumps induces hyperpolarization of membrane potential and inhibit neural firing, light-driven ion-pumping rhodopsins are mostly applied as inhibitory optogenetics tools. Recent progress in genome and metagenome sequencing identified more than several thousands of ion-pumping rhodopsins from a wide variety of microbes, and functional characterization studies has been revealing many new types of light-driven ion pumps one after another. Since light-gated channels were reviewed in other chapters in this book, here the rapid progress in functional characterization, molecular mechanism study, and optogenetic application of ion-pumping rhodopsins were reviewed.
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Affiliation(s)
- Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, Chiba, Japan.
- PRESTO, Japan Science and Technology Agency, Saitama, Japan.
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49
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Zhou Z, Shen Z, Cheng Z, Zhang G, Li M, Li Y, Zhan S, Crittenden JC. Mechanistic insights for efficient inactivation of antibiotic resistance genes: a synergistic interfacial adsorption and photocatalytic-oxidation process. Sci Bull (Beijing) 2020; 65:2107-2119. [PMID: 36732964 DOI: 10.1016/j.scib.2020.07.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 05/20/2020] [Accepted: 06/22/2020] [Indexed: 02/04/2023]
Abstract
Advanced oxidation processes (AOPs) have been applied to address multiple environmental concerns including antibiotic resistance genes (ARGs). ARGs have shown an increasing threat to human health, and they are either harbored by antibiotic-resistant bacteria (ARB) or free in the environment. However, the control of ARGs has been substantially limited by their low concentration and the limited knowledge about their interfacial behavior. Herein, a novel AOP catalyst, Ag/TiO2/graphene oxide (GO), combined with a polyvinylidene fluoride (PVDF) ultrafiltration membrane was designed with a synergistic interfacial adsorption and oxidation function to inactivate ARGs with high efficiency in both model solutions and in secondary wastewater effluent, especially when the residue concentration was low. Further analysis showed that the mineralization of bases and phosphodiesters mainly caused the inactivation of ARGs. Moreover, the interfacial adsorption and oxidation processes of ARGs were studied at the molecular level. The results showed that GO was rich in sp2 backbones and functional oxygen groups, which efficiently captured and enriched the ARGs via π-π interactions and hydrogen bonds. Therefore, the photogenerated active oxygen species attack the ARGs by partially overcoming the kinetic problems in this process. The Ag/TiO2/GO catalyst was further combined with a PVDF membrane to test its potential in wastewater treatment applications. This work offers an efficient method and a corresponding material for the inactivation and mineralization of intra/extracellular ARGs. Moreover, the molecular-level understanding of ARG behaviors on a solid-liquid interface will inspire further control strategies of ARGs in the future.
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Affiliation(s)
- Zhiruo Zhou
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Zhurui Shen
- School of Materials Science and Engineering, Nankai University, Tianjin 300350, China.
| | - Zhihui Cheng
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Guan Zhang
- School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen (HITSZ), Shenzhen 518055, China
| | - Mingmei Li
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Yi Li
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
| | - Sihui Zhan
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; Tianjin Key Laboratory for Rare Earth Materials and Applications, Tianjin 300072, China.
| | - John C Crittenden
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
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50
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Zhang S, Lu Y, Sun X, Li Z, Dang T, Liu S. Proton transfer in polyamine-P 2Mo 5 model adducts: exploring the effect of polyamine cations on their proton conductivity. Dalton Trans 2020; 49:17301-17309. [PMID: 33205793 DOI: 10.1039/d0dt03446k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Constructing acid-base pairs is one of the efficient strategies for the design of proton conductors with high conductivity, due to the ultrafast proton-hopping with a low energy barrier between a proton donor (acid group) and an acceptor (base group). In this study, an acid-base adduct polyamine-P2Mo5 model system was established, including adducts [C6N4H22][H2P2Mo5O23]·H2O (P2Mo5-TETA), [C4N3H16]2[P2Mo5O23]·H2O (P2Mo5-DETA), and [C2N2H10]2[H2P2Mo5O23] (P2Mo5-EN), (TETA = triethylenetetramine, DETA = diethylenetriamine, EN = ethanediamine). Proton conductivity analyses showed that adduct P2Mo5-EN exhibited the highest proton conductivity 1.13 × 10-2 S cm-1 at 65 °C and 95% RH, which was one and three orders of magnitude greater than those of P2Mo5-DETA and P2Mo5-TETA under the same conditions. Ea values of all three adducts are lower than 0.4 eV, which indicates that their proton transfer is attributed to the Grotthuss mechanism. Combined with visual structure analysis, the proton transport pathways of three adducts are highlighted. Moreover, we use this model system to discuss in detail the effect of pKa, proton density and size of polyamine molecules on the proton conductivity of organic amine-POM adducts.
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Affiliation(s)
- Shan Zhang
- Key Laboratory of Polyoxometalate Science of the Ministry of Education, College of Chemistry, Northeast Normal University, Changchun, Jilin 130024, P. R. China.
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