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Temperini ME, Polito R, Venanzi T, Baldassarre L, Hu H, Ciracì C, Pea M, Notargiacomo A, Mattioli F, Ortolani M, Giliberti V. An Infrared Nanospectroscopy Technique for the Study of Electric-Field-Induced Molecular Dynamics. NANO LETTERS 2024; 24:9808-9815. [PMID: 39089683 PMCID: PMC11328210 DOI: 10.1021/acs.nanolett.4c01387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Static electric fields play a considerable role in a variety of molecular nanosystems as diverse as single-molecule junctions, molecules supporting electrostatic catalysis, and biological cell membranes incorporating proteins. External electric fields can be applied to nanoscale samples with a conductive atomic force microscopy (AFM) probe in contact mode, but typically, no structural information is retrieved. Here we combine photothermal expansion infrared (IR) nanospectroscopy with electrostatic AFM probes to measure nanometric volumes where the IR field enhancement and the static electric field overlap spatially. We leverage the vibrational Stark effect in the polymer poly(methyl methacrylate) for calibrating the local electric field strength. In the relevant case of membrane protein bacteriorhodopsin, we observe electric-field-induced changes of the protein backbone conformation and residue protonation state. The proposed technique also has the potential to measure DC currents and IR spectra simultaneously, insofar enabling the monitoring of the possible interplay between charge transport and other effects.
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Affiliation(s)
- Maria Eleonora Temperini
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
- Center for Life Nano- & Neuro-Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, I-00161 Roma, Italy
| | - Raffaella Polito
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Tommaso Venanzi
- Center for Life Nano- & Neuro-Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, I-00161 Roma, Italy
| | - Leonetta Baldassarre
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Huatian Hu
- Center for Biomolecular Nanotechnologies, Istituto Italiano di Tecnologia, Via Barsanti 14, I-73010 Arnesano, Italy
| | - Cristian Ciracì
- Center for Biomolecular Nanotechnologies, Istituto Italiano di Tecnologia, Via Barsanti 14, I-73010 Arnesano, Italy
| | - Marialilia Pea
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere 100, I-00133 Roma, Italy
| | - Andrea Notargiacomo
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere 100, I-00133 Roma, Italy
| | - Francesco Mattioli
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere 100, I-00133 Roma, Italy
| | - Michele Ortolani
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
- Center for Life Nano- & Neuro-Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, I-00161 Roma, Italy
| | - Valeria Giliberti
- Center for Life Nano- & Neuro-Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, I-00161 Roma, Italy
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2
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Gonzalez BD, Forbrig E, Yao G, Kielb P, Mroginski MA, Hildebrandt P, Kozuch J. Cation Dependence of Enniatin B/Membrane-Interactions Assessed Using Surface-Enhanced Infrared Absorption (SEIRA) Spectroscopy. Chempluschem 2024; 89:e202400159. [PMID: 38700478 DOI: 10.1002/cplu.202400159] [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: 02/28/2024] [Revised: 04/26/2024] [Accepted: 04/29/2024] [Indexed: 05/05/2024]
Abstract
Enniatins are mycotoxins with well-known antibacterial, antifungal, antihelmintic and antiviral activity, which have recently come to attention as potential mitochondriotoxic anticancer agents. The cytotoxicity of enniatins is traced back to ionophoric properties, in which the cyclodepsipeptidic structure results in enniatin:cation-complexes of various stoichiometries proposed as membrane-active species. In this work, we employed a combination of surface-enhanced infrared absorption (SEIRA) spectroscopy, tethered bilayer lipid membranes (tBLMs) and density functional theory (DFT)-based computational spectroscopy to monitor the cation-dependence (Mz+=Na+, K+, Cs+, Li+, Mg2+, Ca2+) on the mechanism of enniatin B (EB) incorporation into membranes and identify the functionally relevant EBn : Mz+ complexes formed. We find that Na+ promotes a cooperative incorporation, modelled via an autocatalytic mechanism and mediated by a distorted 2 : 1-EB2 : Na+ complex. K+ (and Cs+) leads to a direct but less efficient insertion into membranes due to the adoption of "ideal" EB2 : K+ sandwich complexes. In contrast, the presence of Li+, Mg2+, and Ca2+ causes a (partial) extraction of EB from the membrane via the formation of "belted" 1 : 1-EB : Mz+ complexes, which screen the cationic charge less efficiently. Our results point to a relevance of the cation dependence for the transport into the malignant cells where the mitochondriotoxic anticancer activity is exerted.
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Affiliation(s)
- Barbara Daiana Gonzalez
- Institut für Chemie, Technische Universität Berlin, Sekr. PC14, Straße des 17. Juni 135, D-10623, Berlin, Germany
| | - Enrico Forbrig
- Institut für Chemie, Technische Universität Berlin, Sekr. PC14, Straße des 17. Juni 135, D-10623, Berlin, Germany
| | - Guiyang Yao
- Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, D-10623, Berlin, Germany
| | - Patrycja Kielb
- Clausius Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstr. 12, D-53115, Bonn, Germany
- Transdisciplinary Research Area', Building Blocks of Matter and Fundamental Interactions (TRA Matter), Universität Bonn, D-53115, Bonn, Germany
| | - Maria Andrea Mroginski
- Institut für Chemie, Technische Universität Berlin, Sekr. PC14, Straße des 17. Juni 135, D-10623, Berlin, Germany
| | - Peter Hildebrandt
- Institut für Chemie, Technische Universität Berlin, Sekr. PC14, Straße des 17. Juni 135, D-10623, Berlin, Germany
| | - Jacek Kozuch
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, D-14195, Berlin, Germany
- Forschungsbau SupraFAB, Freie Universität Berlin, Altensteinstr. 23a, D-14195, Berlin, Germany
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3
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Li Y, Ding J, Qin W. Enhanced Selectivity in Microdroplet-Mediated Enzyme Catalysis. J Am Chem Soc 2024. [PMID: 39073863 DOI: 10.1021/jacs.4c06171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Natural enzymes with enhanced catalytic activity and selectivity have long been studied by tuning the microenvironment around the active site, but how to modulate the active-site electric field in a simple fashion remains challenging. Here, we demonstrate that microdroplets as a simple yet versatile reactor can enhance the electric field at the active site of an enzyme. By using horseradish peroxidase as a model, improved selectivity in microdroplet-mediated enzyme catalysis can be obtained. Quantum mechanical/molecular dynamics calculations and vibrational Stark spectroscopy reveal that the electric field at the microdroplet interface can influence the electrostatic preorganization and orientation of the enzyme to enhance its internal electric field. As a result, the free energies of the substrate and heme can be tuned by the internal electric field, thereby changing its catalytic reaction pathway for a classical substrate, 3,3',5,5'-tetramethylbenzidine, and enabling selective C-N additions for specific substrates. This finding provides a green, simple, and effective way to modulate enzyme-catalyzed reactions and holds promise for a broad spectrum of biosensing and biosynthesis applications.
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Affiliation(s)
- Yinhao Li
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong 264003, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jiawang Ding
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong 264003, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Wei Qin
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong 264003, P. R. China
- Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, Shandong 266237, P. R. China
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, Shandong 266071, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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4
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Chaturvedi SS, Vargas S, Ajmera P, Alexandrova AN. Directed Evolution of Protoglobin Optimizes the Enzyme Electric Field. J Am Chem Soc 2024. [PMID: 38848547 DOI: 10.1021/jacs.4c03914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2024]
Abstract
To unravel why computational design fails in creating viable enzymes, while directed evolution (DE) succeeds, our research delves into the laboratory evolution of protoglobin. DE has adapted this protein to efficiently catalyze carbene transfer reactions. We show that the previously proposed enhanced substrate access and binding alone cannot account for increased yields during DE. The 3D electric field in the entire active site is tracked through protein dynamics, clustered using the affinity propagation algorithm, and subjected to principal component analysis. This analysis reveals notable changes in the electric field with DE, where distinct field topologies influence transition state energetics and mechanism. A chemically meaningful field component emerges and takes the lead during DE and facilitates crossing the barrier to carbene transfer. Our findings underscore intrinsic electric field dynamic's influence on enzyme function, the ability of the field to switch mechanisms within the same protein, and the crucial role of the field in enzyme design.
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Affiliation(s)
- Shobhit S Chaturvedi
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Santiago Vargas
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Pujan Ajmera
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Anastassia N Alexandrova
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
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5
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Cruz R, Ataka K, Heberle J, Kozuch J. Evaluating aliphatic CF, CF2, and CF3 groups as vibrational Stark effect reporters. J Chem Phys 2024; 160:204308. [PMID: 38814010 DOI: 10.1063/5.0198303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 05/09/2024] [Indexed: 05/31/2024] Open
Abstract
Given the extensive use of fluorination in molecular design, it is imperative to understand the solvation properties of fluorinated compounds and the impact of the C-F bond on electrostatic interactions. Vibrational spectroscopy can provide direct insights into these interactions by using the C-F bond stretching [v(C-F)] as an electric field probe through the vibrational Stark effect (VSE). In this work, we explore the VSE of the three basic patterns of aliphatic fluorination, i.e., mono-, di-, and trifluorination in CF, CF2, and CF3 groups, respectively, and compare their response to the well-studied aromatic v(C-F). Magnitudes (i.e., Stark tuning rates) and orientations of the difference dipole vectors of the v(C-F)-containing normal modes were determined using density functional theory and a molecular dynamics (MD)-assisted solvatochromic analysis of model compounds in solvents of varying polarity. We obtain Stark tuning rates of 0.2-0.8 cm-1/(MV/cm), with smallest and largest electric field sensitivities for CFaliphatic and CF3,aliphatic, respectively. While average electric fields of solvation were oriented along the main symmetry axis of the CFn, and thus along its static dipole, the Stark tuning rate vectors were tilted by up to 87° potentially enabling to map electrostatics in multiple dimensions. We discuss the influence of conformational heterogeneity on spectral shifts and point out the importance of multipolar and/or polarizable MD force fields to describe the electrostatics of fluorinated molecules. The implications of this work are of direct relevance for studies of fluorinated molecules as found in pharmaceuticals, fluorinated peptides, and proteins.
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Affiliation(s)
- R Cruz
- Fachbereich Physik, Freie Universität Berlin, Berlin 14195, Germany
| | - K Ataka
- Fachbereich Physik, Freie Universität Berlin, Berlin 14195, Germany
| | - J Heberle
- Fachbereich Physik, Freie Universität Berlin, Berlin 14195, Germany
- Forschungsbau SupraFAB, Freie Universität Berlin, Berlin 14195, Germany
| | - J Kozuch
- Fachbereich Physik, Freie Universität Berlin, Berlin 14195, Germany
- Forschungsbau SupraFAB, Freie Universität Berlin, Berlin 14195, Germany
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6
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Feng RR, Wang M, Zhang W, Gai F. Unnatural Amino Acids for Biological Spectroscopy and Microscopy. Chem Rev 2024; 124:6501-6542. [PMID: 38722769 DOI: 10.1021/acs.chemrev.3c00944] [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: 05/23/2024]
Abstract
Due to advances in methods for site-specific incorporation of unnatural amino acids (UAAs) into proteins, a large number of UAAs with tailored chemical and/or physical properties have been developed and used in a wide array of biological applications. In particular, UAAs with specific spectroscopic characteristics can be used as external reporters to produce additional signals, hence increasing the information content obtainable in protein spectroscopic and/or imaging measurements. In this Review, we summarize the progress in the past two decades in the development of such UAAs and their applications in biological spectroscopy and microscopy, with a focus on UAAs that can be used as site-specific vibrational, fluorescence, electron paramagnetic resonance (EPR), or nuclear magnetic resonance (NMR) probes. Wherever applicable, we also discuss future directions.
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Affiliation(s)
- Ran-Ran Feng
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Manxi Wang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Wenkai Zhang
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Feng Gai
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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7
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Sakpal S, Chakrabarty S, Reddy KD, Deshmukh SH, Biswas R, Bagchi S, Ghosh A. Perturbation of Fermi Resonance on Hydrogen-Bonded > C═O: 2D IR Studies of Small Ester Probes. J Phys Chem B 2024. [PMID: 38686937 DOI: 10.1021/acs.jpcb.3c06698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
We utilized linear and 2D infrared spectroscopy to analyze the carbonyl stretching modes of small esters in different solvents. Particularly noteworthy were the distinct carbonyl spectral line shapes in aqueous solutions, prompting our investigation of the underlying factors responsible for these differences. Through our experimental and theoretical calculations, we identified the presence of the hydrogen-bond-induced Fermi resonance as the primary contributor to the varied line shapes of small esters in aqueous solutions. Furthermore, our findings revealed that the skeletal deformation mode plays a crucial role in the Fermi resonance for all small esters. Specifically, the first overtone band of the skeletal deformation mode intensifies when hydrogen bonds form with the carbonyl group of esters, whereas such coupling is rare in aprotic organic solvents. These spectral insights carry significant implications for the utilization of esters as infrared probes in both biological and chemical systems.
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Affiliation(s)
- Sushil Sakpal
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Suranjana Chakrabarty
- Department of Condensed Matter Physics and Materials Sciences, S. N. Bose National Centre for Basic Sciences, Kolkata 700106, India
| | - Kambham Devendra Reddy
- Department of Chemistry, Indian Institute of Technology Tirupati, Tirupati, Andhra Pradesh, India 517619
| | - Samadhan H Deshmukh
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Rajib Biswas
- Department of Chemistry, Indian Institute of Technology Tirupati, Tirupati, Andhra Pradesh, India 517619
| | - Sayan Bagchi
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Anup Ghosh
- Department of Condensed Matter Physics and Materials Sciences, S. N. Bose National Centre for Basic Sciences, Kolkata 700106, India
- Department of Chemical Science, Bose Institute, Kolkata 700091, India
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8
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Meyer KAE, Garand E. The impact of solvation on the structure and electric field strength in Li +GlyGly complexes. Phys Chem Chem Phys 2024; 26:12406-12421. [PMID: 38623633 DOI: 10.1039/d3cp06264c] [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
To scrutinise the impact of electric fields on the structure and vibrations of biomolecules in the presence of water, we study the sequential solvation of lithium diglycine up to three water molecules with cryogenic infrared action spectroscopy. Conformer-specific IR-IR spectroscopy and H2O/D2O isotopic substitution experiments provide most of the information required to decipher the structure of the observed conformers. Additional confirmation is provided by scaled harmonic vibrational frequency calculations using MP2 and DFT. The first water molecule is shown to bind to the Li+ ion, which weakens the electric field experienced by the peptide and as a consequence, also the strength of an internal NH⋯NH2 hydrogen bond in the diglycine backbone. The strength of this hydrogen bond decreases approximately linearly with the number of water molecules as a result of the decreasing electric field strength and coincides with an increase in the number of conformers observed in our spectra. The addition of two water molecules is already sufficient to change the preferred conformation of the peptide backbone, allowing for Li+ coordination to the lone pair of the terminal amine group.
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Affiliation(s)
- Katharina A E Meyer
- University of Wisconsin-Madison, Department of Chemistry, 1101 University Ave, Madison, WI 53706, USA.
| | - Etienne Garand
- University of Wisconsin-Madison, Department of Chemistry, 1101 University Ave, Madison, WI 53706, USA.
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9
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Streu K, Hunsberger S, Patel J, Wan X, Daly CA. Development of a universal method for vibrational analysis of the terminal alkyne C≡C stretch. J Chem Phys 2024; 160:074106. [PMID: 38364010 DOI: 10.1063/5.0185580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 01/07/2024] [Indexed: 02/18/2024] Open
Abstract
The terminal alkyne C≡C stretch has a large Raman scattering cross section in the "silent" region for biomolecules. This has led to many Raman tag and probe studies using this moiety to study biomolecular systems. A computational investigation of these systems is vital to aid in the interpretation of these results. In this work, we develop a method for computing terminal alkyne vibrational frequencies and isotropic transition polarizabilities that can easily and accurately be applied to any terminal alkyne molecule. We apply the discrete variable representation method to a localized version of the C≡C stretch normal mode. The errors of (1) vibrational localization to the terminal alkyne moiety, (2) anharmonic normal mode isolation, and (3) discretization of the Born-Oppenheimer potential energy surface are quantified and found to be generally small and cancel each other. This results in a method with low error compared to other anharmonic vibrational methods like second-order vibrational perturbation theory and to experiments. Several density functionals are tested using the method, and TPSS-D3, an inexpensive nonempirical density functional with dispersion corrections, is found to perform surprisingly well. Diffuse basis functions are found to be important for the accuracy of computed frequencies. Finally, the computation of vibrational properties like isotropic transition polarizabilities and the universality of the localized normal mode for terminal alkynes are demonstrated.
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Affiliation(s)
- Kristina Streu
- Department of Chemistry, Haverford College, 370 Lancaster Ave., Haverford, Pennsylvania 19041, USA
| | - Sara Hunsberger
- Department of Chemistry, Haverford College, 370 Lancaster Ave., Haverford, Pennsylvania 19041, USA
| | - Jeanette Patel
- Department of Chemistry, Haverford College, 370 Lancaster Ave., Haverford, Pennsylvania 19041, USA
| | - Xiang Wan
- Department of Mathematics and Statistics, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, Illinois 60660, USA
| | - Clyde A Daly
- Department of Chemistry, Haverford College, 370 Lancaster Ave., Haverford, Pennsylvania 19041, USA
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de Oliveira AP, Chase W, Confer MP, Walker S, Baghel D, Ghosh A. Colocalization of β-Sheets and Carotenoids in Aβ Plaques Revealed with Multimodal Spatially Resolved Vibrational Spectroscopy. J Phys Chem B 2024; 128:33-44. [PMID: 38124262 PMCID: PMC10851346 DOI: 10.1021/acs.jpcb.3c04782] [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: 12/23/2023]
Abstract
The aggregation of amyloid β(Aβ) peptides is at the heart of Alzheimer's disease development and progression. As a result, amyloid aggregates have been studied extensively in vitro, and detailed structural information on fibrillar amyloid aggregates is available. However, forwarding these structural models to amyloid plaques in the human brain is still a major challenge. The chemistry of amyloid plaques, particularly in terms of the protein secondary structure and associated chemical moieties, remains poorly understood. In this report, we use Raman microspectroscopy to identify the presence of carotenoids in amyloid plaques and demonstrate that the abundance of carotenoids is correlated with the overall protein secondary structure of plaques, specifically to the population of β-sheets. While the association of carotenoids with plaques has been previously identified, their correlation with the β structure has never been identified. To further validate these findings, we have used optical photothermal infrared (O-PTIR) spectroscopy, which is a spatially resolved technique that yields complementary infrared contrast to Raman. O-PTIR unequivocally demonstrates the presence of elevated β-sheets in carotenoid-containing plaques and the lack of β structure in noncarotenoid plaques. Our findings underscore the potential link between anti-inflammatory species as carotenoids to specific secondary structural motifs within Aβ plaques and highlight the possible role of chemically distinct plaques in neuroinflammation, which can uncover new mechanistic insights and lead to new therapeutic strategies for AD.
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Affiliation(s)
| | - William Chase
- Department of Chemistry and Biochemistry, University of Alabama, Tuscaloosa, AL 35401, USA
| | - Matthew P. Confer
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana Champaign, Urbana, Illinois 61801, USA
| | - Savannah Walker
- Department of Chemistry and Biochemistry, University of Alabama, Tuscaloosa, AL 35401, USA
| | - Divya Baghel
- Department of Chemistry and Biochemistry, University of Alabama, Tuscaloosa, AL 35401, USA
| | - Ayanjeet Ghosh
- Department of Chemistry and Biochemistry, University of Alabama, Tuscaloosa, AL 35401, USA
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11
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Zheng C, Ji Z, Mathews II, Boxer SG. Enhanced active-site electric field accelerates enzyme catalysis. Nat Chem 2023; 15:1715-1721. [PMID: 37563323 PMCID: PMC10906027 DOI: 10.1038/s41557-023-01287-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 06/29/2023] [Indexed: 08/12/2023]
Abstract
The design and improvement of enzymes based on physical principles remain challenging. Here we demonstrate that the principle of electrostatic catalysis can be leveraged to substantially improve a natural enzyme's activity. We enhanced the active-site electric field in horse liver alcohol dehydrogenase by replacing the serine hydrogen-bond donor with threonine and replacing the catalytic Zn2+ with Co2+. Based on the electric field enhancement, we make a quantitative prediction of rate acceleration-50-fold faster than the wild-type enzyme-which was in close agreement with experimental measurements. The effects of the hydrogen bonding and metal coordination, two distinct chemical forces, are described by a unified physical quantity-electric field, which is quantitative, and shown here to be additive and predictive. These results suggest a new design paradigm for both biological and non-biological catalysts.
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Affiliation(s)
- Chu Zheng
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Zhe Ji
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | | | - Steven G Boxer
- Department of Chemistry, Stanford University, Stanford, CA, USA.
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12
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Yan S, Ji X, Peng W, Wang B. Evaluating the Transition State Stabilization/Destabilization Effects of the Electric Fields from Scaffold Residues by a QM/MM Approach. J Phys Chem B 2023; 127:4245-4253. [PMID: 37155960 DOI: 10.1021/acs.jpcb.3c01054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The protein scaffolds of enzymes not only provide structural support for the catalytic center but also exert preorganized electric fields for electrostatic catalysis. In recent years, uniform oriented external electric fields (OEEFs) have been widely applied to enzymatic reactions to mimic the electrostatic effects of the environment. However, the electric fields exerted by individual residues in proteins may be quite heterogeneous across the active site, with varying directions and strengths at different positions of the active site. Here, we propose a QM/MM-based approach to evaluate the effects of the electric fields exerted by individual residues in the protein scaffold. In particular, the heterogeneity of the residue electric fields and the effect of the native protein environment can be properly accounted for by this QM/MM approach. A case study of the O-O heterolysis reaction in the catalytic cycle of TyrH shows that (1) for scaffold residues that are relatively far from the active site, the heterogeneity of the residue electric field in the active site is not very significant and the electrostatic stabilization/destabilization due to each residue can be well approximated with the interaction energy between a uniform electric field and the QM region dipole; (2) for scaffold residues near the active site, the residue electric fields can be highly heterogeneous along the breaking O-O bond. In such a case, approximating the residue electric fields as uniform fields may misrepresent the overall electrostatic effect of the residue. The present QM/MM approach can be applied to evaluate the residues' electrostatic impact on enzymatic reactions, which also can be useful in computational optimization of electric fields to boost the enzyme catalysis.
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Affiliation(s)
- Shengheng Yan
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, P. R. China
| | - Xinwei Ji
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, P. R. China
| | - Wei Peng
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, P. R. China
| | - Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, P. R. China
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13
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Eberhart ME, Wilson TR, Johnston NW, Alexandrova AN. Geometry of Charge Density as a Reporter on the Role of the Protein Scaffold in Enzymatic Catalysis: Electrostatic Preorganization and Beyond. J Chem Theory Comput 2023; 19:694-704. [PMID: 36562645 DOI: 10.1021/acs.jctc.2c01060] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Enzymes host active sites inside protein macromolecules, which have diverse, often incredibly complex, and atom-expensive structures. It is an outstanding question what the role of these expensive scaffolds might be in enzymatic catalysis. Answering this question is essential to both enzymology and the design of artificial enzymes with proficiencies that will match those of the best natural enzymes. Protein rigidifying the active site, contrasted with the dynamics and vibrational motion promoting the reaction, as well as long-range electrostatics (also known as electrostatic preorganization) were all proposed as central contributions of the scaffold to the catalysis. Here, we show that all these effects inevitably produce changes in the quantum mechanical electron density in the active site, which in turn defines the reactivity. The phenomena are therefore fundamentally inseparable. The geometry of the electron density-a scalar field characterized by a number of mathematical features such as critical points-is a rigorous and convenient descriptor of enzymatic catalysis and a reporter on the role of the protein. We show how this geometry can be analyzed, linked to the reaction barriers, and report in particular on intramolecular electric fields in enzymes. We illustrate these tools on the studies of electrostatic preorganization in several representative enzyme classes, both natural and artificial. We highlight the forward-looking aspects of the approach.
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Affiliation(s)
- Mark E Eberhart
- Department of Chemistry, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
| | - Timothy R Wilson
- Department of Chemistry, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
| | - Nathaniel W Johnston
- Department of Chemistry, and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
| | - Anastassia N Alexandrova
- Department of Chemistry, and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
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14
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Ji Z, Boxer SG. β-Lactamases Evolve against Antibiotics by Acquiring Large Active-Site Electric Fields. J Am Chem Soc 2022; 144:22289-22294. [PMID: 36399691 PMCID: PMC10075085 DOI: 10.1021/jacs.2c10791] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A compound bound covalently to an enzyme active site can act either as a substrate if the covalent linkage is readily broken up by the enzyme or as an inhibitor if the bond dissociates slowly. We tracked the reactivity of such bonds associated with the rise of the resistance to penicillin G (PenG) in protein evolution from penicillin-binding proteins (PBPs) to TEM β-lactamases and with the development of avibactam (Avb) to overcome the resistance. We found that the ester linkage in PBP-PenG is resistant to hydrolysis mainly due to the small electric fields present in the protein active site. Conversely, the same linkage in the descendant TEM-PenG experiences large electric fields that stabilize the more charge-separated transition state and thus lower the free energy barrier to hydrolysis. Specifically, the electric fields were improved from -59 to -140 MV/cm in an ancient evolution dating back billions of years, contributing 5 orders of magnitude rate acceleration. This trend continues today in the nullification of newly developed antibiotic drugs. The fast linkage hydrolysis acquired from evolution is counteracted by the upgrade of PenG to Avb whose linkage escapes from the hydrolysis by returning to a low-field environment. Using the framework of electrostatic catalysis, the electric field, an observable from vibrational spectroscopy, provides a unifying physical metric to understand protein evolution and to guide the design of covalent drugs.
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Affiliation(s)
- Zhe Ji
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Steven G Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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15
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Ji Z, Kozuch J, Mathews II, Diercks CS, Shamsudin Y, Schulz MA, Boxer SG. Protein Electric Fields Enable Faster and Longer-Lasting Covalent Inhibition of β-Lactamases. J Am Chem Soc 2022; 144:20947-20954. [PMID: 36324090 PMCID: PMC10066720 DOI: 10.1021/jacs.2c09876] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The widespread design of covalent drugs has focused on crafting reactive groups of proper electrophilicity and positioning toward targeted amino-acid nucleophiles. We found that environmental electric fields projected onto a reactive chemical bond, an overlooked design element, play essential roles in the covalent inhibition of TEM-1 β-lactamase by avibactam. Using the vibrational Stark effect, the magnitudes of the electric fields that are exerted by TEM active sites onto avibactam's reactive C═O were measured and demonstrate an electrostatic gating effect that promotes bond formation yet relatively suppresses the reverse dissociation. These results suggest new principles of covalent drug design and off-target site prediction. Unlike shape and electrostatic complementary which address binding constants, electrostatic catalysis drives reaction rates, essential for covalent inhibition, and deepens our understanding of chemical reactivity, selectivity, and stability in complex systems.
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Affiliation(s)
- Zhe Ji
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Jacek Kozuch
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
- Research Building SupraFAB, Altensteinstreet 23a, 14195 Berlin, Germany
| | - Irimpan I Mathews
- Stanford Synchrotron Radiation Lightsource, Menlo Park, California 94025, United States
| | - Christian S Diercks
- Department of Chemistry, Scripps Research, La Jolla, California 92037, United States
| | - Yasmin Shamsudin
- Department of Chemistry-BMC, Uppsala University, 752 37 Uppsala, Sweden
| | - Mirjam A Schulz
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
- Research Building SupraFAB, Altensteinstreet 23a, 14195 Berlin, Germany
| | - Steven G Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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16
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Mustafa R, Fitian M, Hamilton NB, Li J, Silva WR, Punihaole D. Molecular Insights into the Binding of Linear Polyethylenimines and Single-Stranded DNA Using Raman Spectroscopy: A Quantitative Approach. J Phys Chem B 2022; 126:8404-8414. [PMID: 36222425 PMCID: PMC10413332 DOI: 10.1021/acs.jpcb.2c04939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Establishing how polymeric vectors such as polyethylenimine (PEI) bind and package their nucleic acid cargo is vital toward developing more efficacious and cost-effective gene therapies. To develop a molecular-level picture of DNA binding, we examined how the Raman spectra of PEIs report on their local chemical environment. We find that the intense Raman bands located in the 1400-1500 cm-1 region derive from vibrations with significant CH2 scissoring and NH bending character. The Raman bands that derive from these vibrations show profound intensity changes that depend on both the local dielectric environment and hydrogen bonding interactions with the secondary amine groups on the polymer. We use these bands as spectroscopic markers to assess the binding between low molecular weight PEIs and single-stranded DNA (ssDNA). Analysis of the Raman spectra suggest that PEI primarily binds via electrostatic interactions to the phosphate backbone, which induces the condensation of the ssDNA. We additionally confirm this finding by conducting molecular dynamics simulations. We expect that the spectral correlations determined here will enable future studies to investigate important gene delivery activities, including how PEI interacts with cellular membranes to facilitate cargo internalization into cells.
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Affiliation(s)
- Rusul Mustafa
- Department of Chemistry, University of Vermont, Burlington, Vermont05405, United States
| | - Maria Fitian
- Department of Chemistry and Biochemistry, Siena College, Loudonville, New York12211, United States
| | - Nicholas B Hamilton
- Department of Chemistry, University of Vermont, Burlington, Vermont05405, United States
| | - Jianing Li
- Department of Chemistry, University of Vermont, Burlington, Vermont05405, United States
| | - W Ruchira Silva
- Department of Chemistry and Biochemistry, Siena College, Loudonville, New York12211, United States
| | - David Punihaole
- Department of Chemistry, University of Vermont, Burlington, Vermont05405, United States
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17
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Peng W, Yan S, Zhang X, Liao L, Zhang J, Shaik S, Wang B. How Do Preorganized Electric Fields Function in Catalytic Cycles? The Case of the Enzyme Tyrosine Hydroxylase. J Am Chem Soc 2022; 144:20484-20494. [DOI: 10.1021/jacs.2c09263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wei Peng
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, People Republic of China
| | - Shengheng Yan
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, People Republic of China
| | - Xuan Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, People Republic of China
| | - Langxing Liao
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, People Republic of China
| | - Jinyan Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, People Republic of China
| | - Sason Shaik
- Institute of Chemistry, The Hebrew University of Jerusalem, 9190407 Jerusalem, Israel
| | - Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, People Republic of China
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18
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Role of the electrostatic interactions in the changes in the CN stretching frequency of benzonitrile interacting with hydrogen-bond donating molecules. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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19
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Freindorf M, Delgado AAA, Kraka E. CO bonding in hexa‐ and pentacoordinate carboxy‐neuroglobin: A quantum mechanics/molecular mechanics and local vibrational mode study. J Comput Chem 2022. [DOI: 10.1002/jcc.26973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Marek Freindorf
- Department of Chemistry Southern Methodist University Dallas Texas USA
| | | | - Elfi Kraka
- Department of Chemistry Southern Methodist University Dallas Texas USA
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20
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Fried SDE, Zheng C, Mao Y, Markland TE, Boxer SG. Solvent Organization and Electrostatics Tuned by Solute Electronic Structure: Amide versus Non-Amide Carbonyls. J Phys Chem B 2022; 126:5876-5886. [PMID: 35901512 PMCID: PMC10081530 DOI: 10.1021/acs.jpcb.2c03095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ability to exploit carbonyl groups to measure electric fields in enzymes and other complex reactive environments by using the vibrational Stark effect has inspired growing interest in how these fields can be measured, tuned, and ultimately designed. Previous studies have concentrated on the role of the solvent in tuning the fields exerted on the solute. Here, we explore instead the role of the solute electronic structure in modifying the local solvent organization and electric field exerted on the solute. By measuring the infrared absorption spectra of amide-containing molecules, as prototypical peptides, and contrasting them with non-amide carbonyls in a wide range of solvents, we show that these solutes experience notable differences in their frequency shifts in polar solvents. Using vibrational Stark spectroscopy and molecular dynamics simulations, we demonstrate that while some of these differences can be rationalized by using the distinct intrinsic Stark tuning rates of the solutes, the larger frequency shifts for amides and dimethylurea primarily result from the larger solvent electric fields experienced by their carbonyl groups. These larger fields arise due to their stronger p-π conjugation, which results in larger C═O bond dipole moments that further induce substantial solvent organization. Using electronic structure calculations, we decompose the electric fields into contributions from solvent molecules that are in the first solvation shell and those from the bulk and show that both of these contributions are significant and become larger with enhanced conjugation in solutes. These results show that structural modifications of a solute can be used to tune both the solvent organization and electrostatic environment, indicating the importance of a solute-centric paradigm in modulating and designing the electrostatic environment in condensed-phase chemical processes.
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Affiliation(s)
- Steven D E Fried
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Chu Zheng
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Yuezhi Mao
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Thomas E Markland
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Steven G Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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21
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Kremer F, Kipnusu WK, Fränzl M. Orientation Polarization Spectroscopy-Toward an Atomistic Understanding of Dielectric Relaxation Processes. Int J Mol Sci 2022; 23:ijms23158254. [PMID: 35897823 PMCID: PMC9330800 DOI: 10.3390/ijms23158254] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/21/2022] [Accepted: 07/22/2022] [Indexed: 02/06/2023] Open
Abstract
The theory of orientation polarization and dielectric relaxation was developed by P. Debye more than 100 years ago. It is based on approximating a molecule by a sphere having one or more dipole moments. By that the detailed intra- and intermolecular interactions are explicitly not taken into consideration. In this article, the principal limitations of the Debye approximation are discussed. Taking advantage of the molecular specificity of the infrared (IR) spectral range, measurements of the specific IR absorption of the stretching vibration υ(OH) (at 3370 cm−1) and the asymmetric υas(CH2) (at 2862.9 cm−1) are performed in dependence on the frequency and the strength of external electric fields and at varying temperature. The observed effects are interpreted as caused by orientation polarization of the OH and the adjacent CH2 moieties.
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22
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Geoffroy-Neveux A, Labet V, Alikhani ME. Influence of an Oriented External Electric Field on the Mechanism of Double Proton Transfer between Pyrazole and Guanidine: from an Asynchronous Plateau Transition State to a Synchronous or Stepwise Mechanism. J Phys Chem A 2022; 126:3057-3071. [PMID: 35544749 DOI: 10.1021/acs.jpca.1c10553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The double proton transfer (DPT) reaction between pyrazole and guanidine, a concerted reaction but strongly asynchronous and presenting a "plateau transition region", has been theoretically reinvestigated in the presence of an external uniform electric field. First, we computed the reaction path by DFT and proposed a very detailed description of the constitutive electronic events, based on the ELF topology and the bond evolution theory. Then, we studied the effect of an oriented external electric field (OEEF) on the reaction mechanism, for an OEEF oriented along the proton transfer axis. We observe that in one direction, the DPT reaction can be transformed into a stepwise reaction, going through a stabilized single proton transferred intermediate. Contrarily, the two proton transfers occur simultaneously when the electric field is applied in the opposite direction. In the latter case, the order in which the two protons are transferred in the same elementary step can even be reversed if the OEEF is intense enough. Finally, it has been shown that the evolution of the double proton transfer reaction in the presence of an electric field could be quantitatively anticipated by analyzing the ELF value at the bifurcation point between V(A, H) proton donor and V(B) proton acceptor of the double hydrogen bonded complex in the entrance channel.
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Affiliation(s)
| | - Vanessa Labet
- MONARIS UMR 8233 CNRS, Sorbonne Université, 4 place Jussieu, 75252 Paris Cedex 05, France
| | - M Esmail Alikhani
- MONARIS UMR 8233 CNRS, Sorbonne Université, 4 place Jussieu, 75252 Paris Cedex 05, France
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23
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A two-directional vibrational probe reveals different electric field orientations in solution and an enzyme active site. Nat Chem 2022; 14:891-897. [PMID: 35513508 PMCID: PMC10082611 DOI: 10.1038/s41557-022-00937-w] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 03/25/2022] [Indexed: 12/26/2022]
Abstract
The catalytic power of an electric field depends on its magnitude and orientation with respect to the reactive chemical species. Understanding and designing new catalysts for electrostatic catalysis thus requires methods to measure the electric field orientation and magnitude at the molecular scale. We demonstrate that electric field orientations can be extracted using a two-directional vibrational probe by exploiting the vibrational Stark effect of both the C=O and C-D stretches of a deuterated aldehyde. Combining spectroscopy with molecular dynamics and electronic structure partitioning methods, we demonstrate that, despite distinct polarities, solvents act similarly in their preference for electrostatically stabilizing large bond dipoles at the expense of destabilizing small ones. In contrast, we find that for an active-site aldehyde inhibitor of liver alcohol dehydrogenase, the electric field orientation deviates markedly from that found in solvents, which provides direct evidence for the fundamental difference between the electrostatic environment of solvents and that of a preorganized enzyme active site.
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24
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Weaver JB, Kozuch J, Kirsh JM, Boxer SG. Nitrile Infrared Intensities Characterize Electric Fields and Hydrogen Bonding in Protic, Aprotic, and Protein Environments. J Am Chem Soc 2022; 144:7562-7567. [PMID: 35467853 PMCID: PMC10082610 DOI: 10.1021/jacs.2c00675] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitriles are widely used vibrational probes; however, the interpretation of their IR frequencies is complicated by hydrogen bonding (H-bonding) in protic environments. We report a new vibrational Stark effect (VSE) that correlates the electric field projected on the -C≡N bond to the transition dipole moment and, by extension, the nitrile peak area or integrated intensity. This linear VSE applies to both H-bonding and non-H-bonding interactions. It can therefore be generally applied to determine electric fields in all environments. Additionally, it allows for semiempirical extraction of the H-bonding contribution to the blueshift of the nitrile frequency. Nitriles were incorporated at H-bonding and non-H-bonding protein sites using amber suppression, and each nitrile variant was structurally characterized at high resolution. We exploited the combined information available from variations in frequency and integrated intensity and demonstrate that nitriles are a generally useful probe for electric fields.
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Affiliation(s)
- Jared Bryce Weaver
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
| | - Jacek Kozuch
- Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Jacob M Kirsh
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
| | - Steven G Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
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25
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Yu B, Pletka CC, Iwahara J. Protein Electrostatics Investigated through Paramagnetic NMR for Nonpolar Groups. J Phys Chem B 2022; 126:2196-2202. [PMID: 35266708 PMCID: PMC8973454 DOI: 10.1021/acs.jpcb.1c10930] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Experimental validation of theoretical models for protein electrostatics remains rare. Recently, we have developed a paramagnetic NMR-based method for de novo determination of effective near-surface electrostatic potentials, which allows for straightforward examination of electrostatic models for biomolecules. In the current work, we expand this method and demonstrate that effective near-surface electrostatic potentials can readily be determined from 1H paramagnetic relaxation enhancement (PRE) data for protein CαH and CH3 groups. The experimental data were compared with those predicted from the Poisson-Boltzmann theory. The impact of structural dynamics on the effective near-surface electrostatic potentials was also assessed. The agreement between the experimental and theoretical data was particularly good for methyl 1H nuclei. Compared to the conventional pKa-based validation, our paramagnetic NMR-based approach can provide a far larger number of experimental data that can directly be used to examine the validity of theoretical electrostatic models for proteins.
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26
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Lai Z, Bai C, Sun L, Jia Q, Gao K, Zhang B. Tribology Dependence of Annealed a-C:H Films in Dry Air and Methanol Environments. ACS OMEGA 2022; 7:7472-7480. [PMID: 35284727 PMCID: PMC8908485 DOI: 10.1021/acsomega.1c05105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 01/21/2022] [Indexed: 06/14/2023]
Abstract
In the present study, we obtained a-C:H films with different nanostructures by annealing from room temperature to 400 °C. The influence of the nanostructures on tribological performance in dry air and methanol environments was investigated by a reciprocating tribometer. Our results show that the tribological performance of a-C:H films follows different rules in the two environments. In dry air, tribological properties are controlled by the transfer film and mechanical properties. In methanol, friction and wear are determined by the hydrogen bonding structure, where friction coefficients relate on saturation effects of sp3-CH, and the wear properties depend on the "collapse effect" that the more the sp3-CH3 and sp3-CH2, the easier the wear out of bulk a-C:H films. Our work provides guidance for the application of a-C:H films in the methanol environment.
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Affiliation(s)
- Zhenguo Lai
- State
Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical
Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- Center
of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Changning Bai
- State
Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical
Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- Center
of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lei Sun
- State
Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical
Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- Center
of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qian Jia
- State
Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical
Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- Center
of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kaixiong Gao
- State
Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical
Physics, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Bin Zhang
- State
Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical
Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- Center
of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
- Dalian
National Laboratory for Clean Energy, Chinese
Academy of Sciences, Dalian 116000, China
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27
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Schneider S, Kozuch J, Boxer SG. The Interplay of Electrostatics and Chemical Positioning in the Evolution of Antibiotic Resistance in TEM β-Lactamases. ACS CENTRAL SCIENCE 2021; 7:1996-2008. [PMID: 34963893 PMCID: PMC8704030 DOI: 10.1021/acscentsci.1c00880] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Indexed: 05/25/2023]
Abstract
The interplay of enzyme active site electrostatics and chemical positioning is important for understanding the origin(s) of enzyme catalysis and the design of novel catalysts. We reconstruct the evolutionary trajectory of TEM-1 β-lactamase to TEM-52 toward extended-spectrum activity to better understand the emergence of antibiotic resistance and to provide insights into the structure-function paradigm and noncovalent interactions involved in catalysis. Utilizing a detailed kinetic analysis and the vibrational Stark effect, we quantify the changes in rates and electric fields in the Michaelis and acyl-enzyme complexes for penicillin G and cefotaxime to ascertain the evolutionary role of electric fields to modulate function. These data are combined with MD simulations to interpret and quantify the substrate-dependent structural changes during evolution. We observe that this evolutionary trajectory utilizes a large preorganized electric field and substrate-dependent chemical positioning to facilitate catalysis. This governs the evolvability, substrate promiscuity, and protein fitness landscape in TEM β-lactamase antibiotic resistance.
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Affiliation(s)
| | | | - Steven G. Boxer
- Chemistry Department, Stanford University, Stanford, California 94305, United States
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28
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Zakem G, Ro I, Finzel J, Christopher P. Support functionalization as an approach for modifying activation entropies of catalytic reactions on atomically dispersed metal sites. J Catal 2021. [DOI: 10.1016/j.jcat.2021.07.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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29
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Drexler CI, Cracchiolo OM, Myers RL, Okur HI, Serrano AL, Corcelli SA, Cremer PS. Local Electric Fields in Aqueous Electrolytes. J Phys Chem B 2021; 125:8484-8493. [PMID: 34313130 DOI: 10.1021/acs.jpcb.1c03257] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Vibrational Stark shifts were explored in aqueous solutions of organic molecules with carbonyl- and nitrile-containing constituents. In many cases, the vibrational resonances from these moieties shifted toward lower frequency as salt was introduced into solution. This is in contrast to the blue-shift that would be expected based upon Onsager's reaction field theory. Salts containing well-hydrated cations like Mg2+ or Li+ led to the most pronounced Stark shift for the carbonyl group, while poorly hydrated cations like Cs+ had the greatest impact on nitriles. Moreover, salts containing I- gave rise to larger Stark shifts than those containing Cl-. Molecular dynamics simulations indicated that cations and anions both accumulate around the probe in an ion- and probe-dependent manner. An electric field was generated by the ion pair, which pointed from the cation to the anion through the vibrational chromophore. This resulted from solvent-shared binding of the ions to the probes, consistent with their positions in the Hofmeister series. The "anti-Onsager" Stark shifts occur in both vibrational spectroscopy and fluorescence measurements.
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Affiliation(s)
| | - Olivia M Cracchiolo
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | | | - Halil I Okur
- Department of Chemistry and National Nanotechnology Research Center (UNAM), Bilkent University, 06800 Ankara, Turkey
| | - Arnaldo L Serrano
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Steven A Corcelli
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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30
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Delley MF, Nichols EM, Mayer JM. Interfacial Acid-Base Equilibria and Electric Fields Concurrently Probed by In Situ Surface-Enhanced Infrared Spectroscopy. J Am Chem Soc 2021; 143:10778-10792. [PMID: 34253024 DOI: 10.1021/jacs.1c05419] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Understanding how applied potentials and electrolyte solution conditions affect interfacial proton (charge) transfers at electrode surfaces is critical for electrochemical technologies. Herein, we examine mixed self-assembled monolayers (SAMs) of 4-mercaptobenzoic acid (4-MBA) and 4-mercaptobenzonitrile (4-MBN) on gold using in situ surface-enhanced infrared absorption spectroscopy (SEIRAS). Measurements as a function of the applied potential, the electrolyte pD, and the electrolyte concentration determined both the relative surface populations of acidic and basic forms of 4-MBA, as well as the local electric fields at the SAM-solution interface by following the Stark shifts of 4-MBN. The effective acidity of the SAM varied with the applied potential, requiring a 600 mV change to move the pKa by one unit. Since this is ca. 10× the Nernstian value of 59 mV/pKa, ∼90% of the applied potential dropped across the SAM layer. This emphasizes the importance of distinguishing applied potentials from the potential experienced at the interface. We use the measured interfacial electric fields to estimate the experienced potential at the SAM edge. The SAM pKa showed a roughly Nernstian dependence on this estimated experienced potential. An analysis of the combined acid-base equilibria and Stark shifts reveals that the interfacial charge density has significant contributions from both SAM carboxylate headgroups and electrolyte components. Ion pairing and ion penetration into the SAM also influence the observed surface acidity. To our knowledge, this study is the first concurrent examination of both effective acidity and electric fields, and highlights the relevance of experienced potentials and specific ion effects at functionalized electrode surfaces.
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Affiliation(s)
- Murielle F Delley
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.,Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Eva M Nichols
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada.,Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - James M Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
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31
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Fick RJ, Liu AY, Nussbaumer F, Kreutz C, Rangadurai A, Xu Y, Sommer RD, Shi H, Scheiner S, Stelling AL. Probing the Hydrogen-Bonding Environment of Individual Bases in DNA Duplexes with Isotope-Edited Infrared Spectroscopy. J Phys Chem B 2021; 125:7613-7627. [PMID: 34236202 PMCID: PMC8311644 DOI: 10.1021/acs.jpcb.1c01351] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
![]()
Measuring the strength
of the hydrogen bonds between DNA base pairs
is of vital importance for understanding how our genetic code is physically
accessed and recognized in cells, particularly during replication
and transcription. Therefore, it is important to develop probes for
these key hydrogen bonds (H-bonds) that dictate events critical to
cellular function, such as the localized melting of DNA. The vibrations
of carbonyl bonds are well-known probes of their H-bonding environment,
and their signals can be observed with infrared (IR) spectroscopy.
Yet, pinpointing a single bond of interest in the complex IR spectrum
of DNA is challenging due to the large number of carbonyl signals
that overlap with each other. Here, we develop a method using isotope
editing and infrared (IR) spectroscopy to isolate IR signals from
the thymine (T) C2=O carbonyl. We use solvatochromatic studies
to show that the TC2=O signal’s position in the IR spectrum
is sensitive to the H-bonding capacity of the solvent. Our results
indicate that C2=O of a single T base within DNA duplexes experiences
weak H-bonding interactions. This finding is consistent with the existence
of a third, noncanonical CH···O H-bond between adenine
and thymine in both Watson–Crick and Hoogsteen base pairs in
DNA.
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Affiliation(s)
- Robert J Fick
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Amy Y Liu
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Felix Nussbaumer
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innsbruck 6020, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innsbruck 6020, Austria
| | - Atul Rangadurai
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Yu Xu
- Department of Chemistry, Duke University, Durham, North Carolina 27710, United States
| | - Roger D Sommer
- Molecular Education, Technology, and Research Innovation Center, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Honglue Shi
- Department of Chemistry, Duke University, Durham, North Carolina 27710, United States
| | - Steve Scheiner
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| | - Allison L Stelling
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, Texas 75080, United States.,Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, United States
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32
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Kozuch J, Schneider SH, Zheng C, Ji Z, Bradshaw RT, Boxer SG. Testing the Limitations of MD-Based Local Electric Fields Using the Vibrational Stark Effect in Solution: Penicillin G as a Test Case. J Phys Chem B 2021; 125:4415-4427. [PMID: 33900769 PMCID: PMC8522303 DOI: 10.1021/acs.jpcb.1c00578] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Noncovalent interactions underlie nearly all molecular processes in the condensed phase from solvation to catalysis. Their quantification within a physically consistent framework remains challenging. Experimental vibrational Stark effect (VSE)-based solvatochromism can be combined with molecular dynamics (MD) simulations to quantify the electrostatic forces in solute-solvent interactions for small rigid molecules and, by extension, when these solutes bind in enzyme active sites. While generalizing this approach toward more complex (bio)molecules, such as the conformationally flexible and charged penicillin G (PenG), we were surprised to observe inconsistencies in MD-based electric fields. Combining synthesis, VSE spectroscopy, and computational methods, we provide an intimate view on the origins of these discrepancies. We observe that the electric fields are correlated to conformation-dependent effects of the flexible PenG side chain, including both the local solvation structure and solute conformational sampling in MD. Additionally, we identified that MD-based electric fields are consistently overestimated in three-point water models in the vicinity of charged groups; this cannot be entirely ameliorated using polarizable force fields (AMOEBA) or advanced water models. This work demonstrates the value of the VSE as a direct method for experiment-guided refinements of MD force fields and establishes a general reductionist approach to calibrating vibrational probes for complex (bio)molecules.
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Affiliation(s)
- Jacek Kozuch
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
| | - Samuel H Schneider
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
| | - Chu Zheng
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
| | - Zhe Ji
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
| | - Richard T Bradshaw
- Department of Chemistry, King's College London, Britannia House, 7 Trinity Street, London SE1 1DB, U.K
| | - Steven G Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
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33
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Baserga F, Dragelj J, Kozuch J, Mohrmann H, Knapp EW, Stripp ST, Heberle J. Quantification of Local Electric Field Changes at the Active Site of Cytochrome c Oxidase by Fourier Transform Infrared Spectroelectrochemical Titrations. Front Chem 2021; 9:669452. [PMID: 33987170 PMCID: PMC8111224 DOI: 10.3389/fchem.2021.669452] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 03/24/2021] [Indexed: 11/30/2022] Open
Abstract
Cytochrome c oxidase (CcO) is a transmembrane protein complex that reduces molecular oxygen to water while translocating protons across the mitochondrial membrane. Changes in the redox states of its cofactors trigger both O2 reduction and vectorial proton transfer, which includes a proton-loading site, yet unidentified. In this work, we exploited carbon monoxide (CO) as a vibrational Stark effect (VSE) probe at the binuclear center of CcO from Rhodobacter sphaeroides. The CO stretching frequency was monitored as a function of the electrical potential, using Fourier transform infrared (FTIR) absorption spectroelectrochemistry. We observed three different redox states (R4CO, R2CO, and O), determined their midpoint potential, and compared the resulting electric field to electrostatic calculations. A change in the local electric field strength of +2.9 MV/cm was derived, which was induced by the redox transition from R4CO to R2CO. We performed potential jump experiments to accumulate the R2CO and R4CO species and studied the FTIR difference spectra in the protein fingerprint region. The comparison of the experimental and computational results reveals that the key glutamic acid residue E286 is protonated in the observed states, and that its hydrogen-bonding environment is disturbed upon the redox transition of heme a3. Our experiments also suggest propionate A of heme a3 changing its protonation state in concert with the redox state of a second cofactor, heme a. This supports the role of propionic acid side chains as part of the proton-loading site.
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Affiliation(s)
- Federico Baserga
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Jovan Dragelj
- Macromolecular Modelling Group, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.,Modeling of Biomolecular Systems, Technische Universität Berlin, Berlin, Germany
| | - Jacek Kozuch
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Hendrik Mohrmann
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Ernst-Walter Knapp
- Macromolecular Modelling Group, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Sven T Stripp
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
| | - Joachim Heberle
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany
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34
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Pagar AD, Patil MD, Flood DT, Yoo TH, Dawson PE, Yun H. Recent Advances in Biocatalysis with Chemical Modification and Expanded Amino Acid Alphabet. Chem Rev 2021; 121:6173-6245. [PMID: 33886302 DOI: 10.1021/acs.chemrev.0c01201] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The two main strategies for enzyme engineering, directed evolution and rational design, have found widespread applications in improving the intrinsic activities of proteins. Although numerous advances have been achieved using these ground-breaking methods, the limited chemical diversity of the biopolymers, restricted to the 20 canonical amino acids, hampers creation of novel enzymes that Nature has never made thus far. To address this, much research has been devoted to expanding the protein sequence space via chemical modifications and/or incorporation of noncanonical amino acids (ncAAs). This review provides a balanced discussion and critical evaluation of the applications, recent advances, and technical breakthroughs in biocatalysis for three approaches: (i) chemical modification of cAAs, (ii) incorporation of ncAAs, and (iii) chemical modification of incorporated ncAAs. Furthermore, the applications of these approaches and the result on the functional properties and mechanistic study of the enzymes are extensively reviewed. We also discuss the design of artificial enzymes and directed evolution strategies for enzymes with ncAAs incorporated. Finally, we discuss the current challenges and future perspectives for biocatalysis using the expanded amino acid alphabet.
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Affiliation(s)
- Amol D Pagar
- Department of Systems Biotechnology, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea
| | - Mahesh D Patil
- Department of Systems Biotechnology, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea
| | - Dillon T Flood
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Tae Hyeon Yoo
- Department of Molecular Science and Technology, Ajou University, 206 World cup-ro, Yeongtong-gu, Suwon 16499, Korea
| | - Philip E Dawson
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Hyungdon Yun
- Department of Systems Biotechnology, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea
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35
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Vieira Silveira E, Montecinos R, Scorsin L, Garcia-Rio L, Medeiros M, Nascimento V, Nome F, Affeldt RF, Micke GA. Supramolecular kinetic effects by pillararenes: the synergism between spatiotemporal and preorganization concepts in decarboxylation reactions. NEW J CHEM 2021. [DOI: 10.1039/d1nj00551k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Spatiotemporal and preorganization factors were both responsible for the catalytic and inhibitory supramolecular effects in decarboxylation reactions.
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Affiliation(s)
| | - Rodrigo Montecinos
- Faculdad de Química
- Pontificia Universidad Católica de Chile
- Santiago
- Chile
| | - Leandro Scorsin
- Department of Chemistry
- Federal University of Santa Catarina
- Florianópolis
- Brazil
| | - Luis Garcia-Rio
- Departamento de Química Física
- Centro de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS)
- Universidade de Santiago de Compostela
- 15782 Santiago de Compostela
- Spain
| | - Michelle Medeiros
- Department of Chemistry
- Federal University of Santa Catarina
- Florianópolis
- Brazil
| | - Vanessa Nascimento
- Department of Organic Chemistry
- Fluminense Federal University
- Niterói
- Brazil
| | - Faruk Nome
- Department of Chemistry
- Federal University of Santa Catarina
- Florianópolis
- Brazil
| | - Ricardo F. Affeldt
- Department of Chemistry
- Federal University of Santa Catarina
- Florianópolis
- Brazil
| | - Gustavo A. Micke
- Department of Chemistry
- Federal University of Santa Catarina
- Florianópolis
- Brazil
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36
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Dixit VA, Warwicker J, Visser SP. How Do Metal Ions Modulate the Rate‐Determining Electron‐Transfer Step in Cytochrome P450 Reactions? Chemistry 2020; 26:15270-15281. [DOI: 10.1002/chem.202003024] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Indexed: 12/16/2022]
Affiliation(s)
- Vaibhav A. Dixit
- Department of Pharmacy Birla Institute of Technology and Sciences Pilani (BITS-Pilani) Vidya Vihar Campus 41 Pilani 333031 Rajasthan India
| | - Jim Warwicker
- Manchester Institute of Biotechnology The University of Manchester 131 Princess Street Manchester M17DN United Kingdom
- Department of Chemistry The University of Manchester Oxford Road Manchester M139PL United Kingdom
| | - Sam P. Visser
- Manchester Institute of Biotechnology The University of Manchester 131 Princess Street Manchester M17DN United Kingdom
- Department of Chemical Engineering and Analytical Science The University of Manchester Oxford Road Manchester M13 9PL United Kingdom
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37
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Freindorf M, Kraka E. Critical assessment of the FeC and CO bond strength in carboxymyoglobin: a QM/MM local vibrational mode study. J Mol Model 2020; 26:281. [DOI: 10.1007/s00894-020-04519-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 08/26/2020] [Indexed: 12/15/2022]
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38
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Cracchiolo OM, Geremia DK, Corcelli SA, Serrano AL. Hydrogen Bond Exchange and Ca2+ Binding of Aqueous N-Methylacetamide Revealed by 2DIR Spectroscopy. J Phys Chem B 2020; 124:6947-6954. [DOI: 10.1021/acs.jpcb.0c02444] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Olivia M. Cracchiolo
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Danielle K. Geremia
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Steven A. Corcelli
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Arnaldo L. Serrano
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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39
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Boda M, Patwari GN. Internal electric fields in methanol [MeOH] 2-6 clusters. Phys Chem Chem Phys 2020; 22:10917-10923. [PMID: 32373804 DOI: 10.1039/c9cp04571f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Water and methanol are well known solvents showing cooperative hydrogen bonding, however the differences in the hydrogen bonding pattern in water and methanol are due to the presence of the methyl group in methanol. The presence of the methyl group leads to formation of C-HO hydrogen bonds apart from the usual O-HO hydrogen bonds. The electric fields evaluated along the hydrogen bonded donor OH and CH groups reveal that the C-HO hydrogen bonds can significantly influence the structure and energetics (by about 20%) of methanol clusters. A linear Stark effect was observed on the hydrogen bonded OH groups in methanol clusters with a Stark tuning rate of 3.1 cm-1 (MV cm-1)-1 as an average behaviour. Furthermore, the Stark tuning of the OH oscillators in methanol depends on their hydrogen bonding environment wherein molecules with the DAA motif show higher rates than the rest. The present work suggests that the OH group of methanol has higher sensitivity as a vibrational probe relative to the OH group of water.
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Affiliation(s)
- Manjusha Boda
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
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40
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Kozuch J, Schneider SH, Boxer SG. Biosynthetic Incorporation of Site-Specific Isotopes in β-Lactam Antibiotics Enables Biophysical Studies. ACS Chem Biol 2020; 15:1148-1153. [PMID: 32175720 DOI: 10.1021/acschembio.9b01054] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A biophysical understanding of the mechanistic, chemical, and physical origins underlying antibiotic action and resistance is vital to the discovery of novel therapeutics and the development of strategies to combat the growing emergence of antibiotic resistance. The site-specific introduction of stable-isotope labels into chemically complex natural products is particularly important for techniques such as NMR, IR, mass spectrometry, imaging, and kinetic isotope effects. Toward this goal, we developed a biosynthetic strategy for the site-specific incorporation of 13C labels into the canonical β-lactam carbonyl of penicillin G and cefotaxime, the latter via cephalosporin C. This was achieved through sulfur-replacement with 1-13C-l-cysteine, resulting in high isotope incorporations and milligram-scale yields. Using 13C NMR and isotope-edited IR difference spectroscopy, we illustrate how these molecules can be used to interrogate interactions with their protein targets, e.g., TEM-1 β-lactamase. This method provides a feasible route to isotopically labeled penicillin and cephalosporin precursors for future biophysical studies.
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Affiliation(s)
- Jacek Kozuch
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
| | - Samuel H. Schneider
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
| | - Steven G. Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States
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41
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Verma N, Tao Y, Zou W, Chen X, Chen X, Freindorf M, Kraka E. A Critical Evaluation of Vibrational Stark Effect (VSE) Probes with the Local Vibrational Mode Theory. SENSORS 2020; 20:s20082358. [PMID: 32326248 PMCID: PMC7219233 DOI: 10.3390/s20082358] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 04/14/2020] [Accepted: 04/15/2020] [Indexed: 02/06/2023]
Abstract
Over the past two decades, the vibrational Stark effect has become an important tool to measure and analyze the in situ electric field strength in various chemical environments with infrared spectroscopy. The underlying assumption of this effect is that the normal stretching mode of a target bond such as CO or CN of a reporter molecule (termed vibrational Stark effect probe) is localized and free from mass-coupling from other internal coordinates, so that its frequency shift directly reflects the influence of the vicinal electric field. However, the validity of this essential assumption has never been assessed. Given the fact that normal modes are generally delocalized because of mass-coupling, this analysis was overdue. Therefore, we carried out a comprehensive evaluation of 68 vibrational Stark effect probes and candidates to quantify the degree to which their target normal vibration of probe bond stretching is decoupled from local vibrations driven by other internal coordinates. The unique tool we used is the local mode analysis originally introduced by Konkoli and Cremer, in particular the decomposition of normal modes into local mode contributions. Based on our results, we recommend 31 polyatomic molecules with localized target bonds as ideal vibrational Stark effect probe candidates.
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Affiliation(s)
- Niraj Verma
- Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, TX 75275-0314, USA; (N.V.); (Y.T.); (M.F.)
| | - Yunwen Tao
- Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, TX 75275-0314, USA; (N.V.); (Y.T.); (M.F.)
| | - Wenli Zou
- Institute of Modern Physics, Northwest University, Xi’an 710127, China;
| | - Xia Chen
- Hubei Key Laboratory of Natural Medicinal Chemistry and Resource Evaluation, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China;
| | - Xin Chen
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China;
| | - Marek Freindorf
- Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, TX 75275-0314, USA; (N.V.); (Y.T.); (M.F.)
| | - Elfi Kraka
- Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, TX 75275-0314, USA; (N.V.); (Y.T.); (M.F.)
- Correspondence:
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42
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Chatterjee S, Haldar T, Ghosh D, Bagchi S. Electrostatic Manifestation of Micro-Heterogeneous Solvation Structures in Deep-Eutectic Solvents: A Spectroscopic Approach. J Phys Chem B 2020; 124:3709-3715. [DOI: 10.1021/acs.jpcb.9b11352] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Srijan Chatterjee
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Tapas Haldar
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Deborin Ghosh
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune 411008, India
| | - Sayan Bagchi
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
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43
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Szczepaniak U, Schneider SH, Horvath R, Kozuch J, Geiser M. Vibrational Stark Spectroscopy of Fluorobenzene Using Quantum Cascade Laser Dual Frequency Combs. APPLIED SPECTROSCOPY 2020; 74:347-356. [PMID: 31868520 DOI: 10.1177/0003702819888503] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We demonstrate the performance of a dual frequency comb quantum cascade laser (QCL) spectrometer for the application of vibrational Stark spectroscopy. Measurements performed on fluorobenzene with the dual-comb spectrometer (DCS) were compared to results obtained using a conventional Fourier transform infrared (FT-IR) instrument in terms of spectral response, parameter estimation, and signal-to-noise ratio (S/N). The dual-comb spectrometer provided similar qualitative and quantitative data as the FT-IR setup in 250 times shorter acquisition time. For fluorobenzene, the DCS measurement resulted in a more precise estimation of the fluorobenzene Stark tuning rate ((0.81 ± 0.09) cm-1/(MV/cm)) than with the FT-IR system ((0.89 ± 0.15) cm-1/(MV/cm)). Both values are in accordance with the previously reported value of 0.84 cm-1/(MV/cm). We also point to an improvement of signal-to-noise ratio in the DCS configuration. Additional characteristics of the dual-comb spectrometer applicable to vibrational Stark spectroscopy and their scaling properties for future applications are discussed.
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Affiliation(s)
| | | | | | - Jacek Kozuch
- Department of Chemistry, Stanford University, Stanford, CA, USA
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44
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Chen SH, Hiramatsu H. Tautomer Structures in Ketose-Aldose Transformation of 1,3-Dihydroxyacetone Studied by Infrared Electroabsorption Spectroscopy. J Phys Chem B 2019; 123:10663-10671. [PMID: 31765151 DOI: 10.1021/acs.jpcb.9b08557] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The acyclic form of monosaccharides exists in a structural equilibrium, with aldose having the aldehyde group and ketose the ketone group (ketose-aldose equilibrium). A basic catalyst facilitates their transformation, which affects the chemical properties of the monosaccharide. In this study, we investigated the ketose-aldose transformation of 1,3-dihydroxyacetone (1,3-DHA), one of the simplest systems of the ketose-aldose equilibrium. We examined the effects of piperidine as the basic catalyst and used IR electroabsorption spectroscopy to study the responses to an external electric field. We analyzed the changes in IR absorption by considering the changes in the molecular orientation and number of molecules in response to the external electric field. The results of the analysis revealed the permanent dipole moment μP, an angle η between μP and μT (the transition moment of the molecular vibration), and the equilibrium constants. The ketose-aldose transformation of 1,3-DHA can be explained in terms of the equilibrium of three states. In the presence of piperidine, a five-state equilibrium was concluded. On the basis of the experimental data, we propose plausible models of dihydroxyacetone, E-enediols, Z-enediol, or glyceraldehyde for each state. The results of our structural analysis of these tautomers provide a detailed understanding of the ketose-aldose transformation of acyclic saccharides and the effects of the basic catalyst.
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Affiliation(s)
- Szu-Hua Chen
- Department of Applied Chemistry and Institute of Molecular Science , National Chiao Tung University , Hsinchu 30010 , Taiwan
| | - Hirotsugu Hiramatsu
- Department of Applied Chemistry and Institute of Molecular Science , National Chiao Tung University , Hsinchu 30010 , Taiwan.,Center for Emergent Functional Matter Science , National Chiao Tung University , Hsinchu 30010 , Taiwan
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Shi Y, Ma W, Gao M, Yang Y. Development of curcumin-loaded methoxy poly(ethylene glycol)-block- poly(caprolactone)-block-poly(1, 4, 8-Trioxa [4.6] spiro-9-undecanone) nanoparticles and studies on their in vitro anti-tumor activities. Colloids Surf B Biointerfaces 2019; 184:110525. [DOI: 10.1016/j.colsurfb.2019.110525] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 09/20/2019] [Accepted: 09/23/2019] [Indexed: 12/14/2022]
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Chatterjee S, Ghosh D, Haldar T, Deb P, Sakpal SS, Deshmukh SH, Kashid SM, Bagchi S. Hydrocarbon Chain-Length Dependence of Solvation Dynamics in Alcohol-Based Deep Eutectic Solvents: A Two-Dimensional Infrared Spectroscopic Investigation. J Phys Chem B 2019; 123:9355-9363. [DOI: 10.1021/acs.jpcb.9b08954] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Srijan Chatterjee
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
| | - Deborin Ghosh
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
| | - Tapas Haldar
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Pranab Deb
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Sushil S. Sakpal
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Samadhan H. Deshmukh
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Somnath M. Kashid
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Sayan Bagchi
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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Li P, Ge Q. Membrane Surface Engineering with Bifunctional Zwitterions for Efficient Oil-Water Separation. ACS APPLIED MATERIALS & INTERFACES 2019; 11:31328-31337. [PMID: 31381295 DOI: 10.1021/acsami.9b09773] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Chemical modification provides a solution to the membrane fouling problem in oily water purification. However, complicated synthesis processes and harsh reaction conditions are frequently encountered with this approach. Here we developed two bifunctional zwitterionic materials, i.e., n-aminoethyl piperazine propanesulfonate (P-SO3-NH2) and 1,4-bis (3-aminopropyl) piperazine propanesulfonate (P-2SO3-2NH2), by a clean method and grafted them onto membrane surface via a fast single-step reaction. These materials endow the resultant membrane a more hydrophilic and smoother surface, significantly improving the water permeability, fouling resistance and recyclability of membrane in forward osmosis oily water reclamation. The water fluxes produced by the P-2SO3-2NH2 modified membrane are 47% (from 20.0 to 29.3 LMH) and 60% (from 16.0 to 25.6 LMH) higher than those of the unmodified membrane when DI water and an oily emulsion (1500 ppm) as the respective feeds. A higher water flux recovery is also achieved for the P-2SO3-2NH2 modified membrane (94%) than that of the nascent membrane (82%) after a 12-h experiment. These promising findings coupled with a facile and efficient membrane modification approach provide inspiration for both membrane exploration and oily water treatment.
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Affiliation(s)
- Ping Li
- College of Environment and Resources , Fuzhou University , Fujian 350116 , P. R. China
| | - Qingchun Ge
- College of Environment and Resources , Fuzhou University , Fujian 350116 , P. R. China
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Shi MW, Thomas SP, Hathwar VR, Edwards AJ, Piltz RO, Jayatilaka D, Koutsantonis GA, Overgaard J, Nishibori E, Iversen BB, Spackman MA. Measurement of Electric Fields Experienced by Urea Guest Molecules in the 18-Crown-6/Urea (1:5) Host-Guest Complex: An Experimental Reference Point for Electric-Field-Assisted Catalysis. J Am Chem Soc 2019; 141:3965-3976. [PMID: 30761898 DOI: 10.1021/jacs.8b12927] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
High-resolution synchrotron and neutron single-crystal diffraction data of 18-crown-6/(pentakis)urea measured at 30 K are combined, with the aim of better appreciating the electrostatics associated with intermolecular interactions in condensed matter. With two 18-crown-6 molecules and five different urea molecules in the crystal, this represents the most ambitious combined X-ray/synchrotron and neutron experimental charge density analysis to date on a cocrystal or host-guest system incorporating such a large number of unique molecules. The dipole moments of the five urea guest molecules in the crystal are enhanced considerably compared to values determined for isolated molecules, and 2D maps of the electrostatic potential and electric field show clearly how the urea molecules are oriented with dipole moments aligned along the electric field exerted by their molecular neighbors. Experimental electric fields in the range of 10-19 GV m-1, obtained for the five different urea environments, corroborate independent measurements of electric fields in the active sites of enzymes and provide an important experimental reference point for recent discussions focused on electric-field-assisted catalysis.
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Affiliation(s)
- Ming W Shi
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , WA 6009 , Australia
| | - Sajesh P Thomas
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , WA 6009 , Australia.,Center for Materials Crystallography and Department of Chemistry , Aarhus University , Langelandsgade 140 , DK-8000 Aarhus C , Denmark
| | - Venkatesha R Hathwar
- Center for Materials Crystallography and Department of Chemistry , Aarhus University , Langelandsgade 140 , DK-8000 Aarhus C , Denmark.,Division of Physics, Faculty of Pure and Applied Sciences , University of Tsukuba , 1-1-1 Tennodai , Tsukuba , Ibaraki 305-8571 , Japan
| | - Alison J Edwards
- Australian Nuclear Science and Technology Organization , Australian Centre for Neutron Scattering , New Illawarra Road , Lucas Heights , New South Wales 2234 , Australia
| | - Ross O Piltz
- Australian Nuclear Science and Technology Organization , Australian Centre for Neutron Scattering , New Illawarra Road , Lucas Heights , New South Wales 2234 , Australia
| | - Dylan Jayatilaka
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , WA 6009 , Australia
| | - George A Koutsantonis
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , WA 6009 , Australia
| | - Jacob Overgaard
- Center for Materials Crystallography and Department of Chemistry , Aarhus University , Langelandsgade 140 , DK-8000 Aarhus C , Denmark
| | - Eiji Nishibori
- Division of Physics, Faculty of Pure and Applied Sciences , University of Tsukuba , 1-1-1 Tennodai , Tsukuba , Ibaraki 305-8571 , Japan
| | - Bo B Iversen
- Center for Materials Crystallography and Department of Chemistry , Aarhus University , Langelandsgade 140 , DK-8000 Aarhus C , Denmark
| | - Mark A Spackman
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , WA 6009 , Australia
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