1
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Hess KA, Rohler CK, Boutwell DR, Snyder JM, Buchanan LE. Suppressing sidechain modes and improving structural resolution for 2D IR spectroscopy via vibrational lifetimes. J Chem Phys 2024; 161:054201. [PMID: 39087534 PMCID: PMC11296734 DOI: 10.1063/5.0207523] [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] [Received: 03/08/2024] [Accepted: 07/15/2024] [Indexed: 08/02/2024] Open
Abstract
Vibrational spectroscopy of protein structure often utilizes 13C18O-labeling of backbone carbonyls to further increase structural resolution. However, sidechains such as arginine, aspartate, and glutamate absorb within the same spectral region, complicating the analysis of isotope-labeled peaks. In this study, we report that the waiting time between pump and probe pulses in two-dimensional infrared spectroscopy can be used to suppress sidechain modes in favor of backbone amide I' modes based on differences in vibrational lifetimes. Furthermore, differences in the lifetimes of 13C18O-amide I' modes can aid in the assignment of secondary structure for labeled residues. Using model disordered and β-sheet peptides, it was determined that while β-sheets exhibit a longer lifetime than disordered structures, amide I' modes in both secondary structures exhibit longer lifetimes than sidechain modes. Overall, this work demonstrates that collecting 2D IR data at delayed waiting times, based on differences in vibrational lifetime between modes, can be used to effectively suppress interfering sidechain modes and further identify secondary structures.
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Affiliation(s)
- Kayla A. Hess
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Lane, Nashville, Tennessee 37235, USA
| | - Cade K. Rohler
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Lane, Nashville, Tennessee 37235, USA
| | - Dalton R. Boutwell
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Lane, Nashville, Tennessee 37235, USA
| | - Jason M. Snyder
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Lane, Nashville, Tennessee 37235, USA
| | - Lauren E. Buchanan
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Lane, Nashville, Tennessee 37235, USA
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2
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Chun SY, Shim JW, Kwak K, Cho M. Molecular Photothermal Effect on the 2D-IR Spectroscopy of Acetonitrile-Based Li-Ion Battery Electrolytes. J Phys Chem Lett 2024; 15:7302-7311. [PMID: 38984794 DOI: 10.1021/acs.jpclett.4c00522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/11/2024]
Abstract
Advancements in Li-ion battery (LIB) technology hinge on an understanding of Li-ion solvation and charge transport dynamics. Ultrafast two-dimensional infrared (2D-IR) spectroscopy has been used to investigate these dynamics in electrolytes by probing chemical exchange processes through time-dependent cross-peak analysis. However, accurate interpretation is complicated by factors such as vibrational energy transfer and molecular photothermal effect (MPTE), affecting cross-peak evolution. Pinpointing the precise origin of these cross-peaks has posed a significant challenge in time-resolved IR spectroscopic studies of LIB electrolytes. Here, we trace the origin of 2D-IR cross-peaks of LIB electrolytes utilizing acetonitrile as a solvent. Time-dependent analysis of LiSCN and CH3SCN mixtures in CD3CN revealed distinctive MPTE features. Furthermore, direct observation of intermolecular MPTE through two-color IR pump-probe spectroscopy lends support to the findings. Our results emphasize the non-negligible artifacts induced by MPTE and the necessity of considering these effects to accurately observe the ultrafast dynamics within LIB electrolytes.
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Affiliation(s)
- So Yeon Chun
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Korea University, Seoul 02841, Republic of Korea
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Joong Won Shim
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Korea University, Seoul 02841, Republic of Korea
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Kyungwon Kwak
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Korea University, Seoul 02841, Republic of Korea
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Minhaeng Cho
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Korea University, Seoul 02841, Republic of Korea
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
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3
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Giubertoni G, Feng L, Klein K, Giannetti G, Rutten L, Choi Y, van der Net A, Castro-Linares G, Caporaletti F, Micha D, Hunger J, Deblais A, Bonn D, Sommerdijk N, Šarić A, Ilie IM, Koenderink GH, Woutersen S. Elucidating the role of water in collagen self-assembly by isotopically modulating collagen hydration. Proc Natl Acad Sci U S A 2024; 121:e2313162121. [PMID: 38451946 PMCID: PMC10945838 DOI: 10.1073/pnas.2313162121] [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: 08/07/2023] [Accepted: 12/30/2023] [Indexed: 03/09/2024] Open
Abstract
Water is known to play an important role in collagen self-assembly, but it is still largely unclear how water-collagen interactions influence the assembly process and determine the fibril network properties. Here, we use the H[Formula: see text]O/D[Formula: see text]O isotope effect on the hydrogen-bond strength in water to investigate the role of hydration in collagen self-assembly. We dissolve collagen in H[Formula: see text]O and D[Formula: see text]O and compare the growth kinetics and the structure of the collagen assemblies formed in these water isotopomers. Surprisingly, collagen assembly occurs ten times faster in D[Formula: see text]O than in H[Formula: see text]O, and collagen in D[Formula: see text]O self-assembles into much thinner fibrils, that form a more inhomogeneous and softer network, with a fourfold reduction in elastic modulus when compared to H[Formula: see text]O. Combining spectroscopic measurements with atomistic simulations, we show that collagen in D[Formula: see text]O is less hydrated than in H[Formula: see text]O. This partial dehydration lowers the enthalpic penalty for water removal and reorganization at the collagen-water interface, increasing the self-assembly rate and the number of nucleation centers, leading to thinner fibrils and a softer network. Coarse-grained simulations show that the acceleration in the initial nucleation rate can be reproduced by the enhancement of electrostatic interactions. These results show that water acts as a mediator between collagen monomers, by modulating their interactions so as to optimize the assembly process and, thus, the final network properties. We believe that isotopically modulating the hydration of proteins can be a valuable method to investigate the role of water in protein structural dynamics and protein self-assembly.
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Affiliation(s)
- Giulia Giubertoni
- Van ’t Hoff Institute for Molecular Sciences, Department of Molecular Photonics, University of Amsterdam, Amsterdam1090 GD, The Netherlands
| | - Liru Feng
- Van ’t Hoff Institute for Molecular Sciences, Department of Molecular Photonics, University of Amsterdam, Amsterdam1090 GD, The Netherlands
| | - Kevin Klein
- Institute of Science and Technology Austria, Division of Mathematical and Physical Sciences, Klosterneuburg3400, Austria
- University College London, Division of Physics and Astronomy, LondonWC1E 6BT, United Kingdom
| | - Guido Giannetti
- Van ’t Hoff Institute for Molecular Sciences, Department of Molecular Photonics, University of Amsterdam, Amsterdam1090 GD, The Netherlands
| | - Luco Rutten
- Electron Microscopy Center, Radboud Technology Center Microscopy, Department of Medical BioSciences, Radboud University Medical Center, Nijmegen6525 GA, The Netherlands
| | - Yeji Choi
- Max Planck Institute for Polymer Research, Molecular Spectroscopy Department, Mainz55128, Germany
| | - Anouk van der Net
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft2628 HZ, The Netherlands
| | - Gerard Castro-Linares
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft2628 HZ, The Netherlands
| | - Federico Caporaletti
- Van ’t Hoff Institute for Molecular Sciences, Department of Molecular Photonics, University of Amsterdam, Amsterdam1090 GD, The Netherlands
- Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Amsterdam1090 GL, The Netherlands
| | - Dimitra Micha
- Amsterdam University Medical Centers, Human Genetics Department, Vrije Universiteit, Amsterdam1007 MB, The Netherlands
| | - Johannes Hunger
- Max Planck Institute for Polymer Research, Molecular Spectroscopy Department, Mainz55128, Germany
| | - Antoine Deblais
- Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Amsterdam1090 GL, The Netherlands
| | - Daniel Bonn
- Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Amsterdam1090 GL, The Netherlands
| | - Nico Sommerdijk
- Electron Microscopy Center, Radboud Technology Center Microscopy, Department of Medical BioSciences, Radboud University Medical Center, Nijmegen6525 GA, The Netherlands
| | - Andela Šarić
- Institute of Science and Technology Austria, Division of Mathematical and Physical Sciences, Klosterneuburg3400, Austria
| | - Ioana M. Ilie
- Van ’t Hoff Institute for Molecular Sciences, Department of Molecular Photonics, University of Amsterdam, Amsterdam1090 GD, The Netherlands
- Amsterdam Center for Multiscale Modeling, University of Amsterdam, Amsterdam1090 GD, The Netherlands
| | - Gijsje H. Koenderink
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft2628 HZ, The Netherlands
| | - Sander Woutersen
- Van ’t Hoff Institute for Molecular Sciences, Department of Molecular Photonics, University of Amsterdam, Amsterdam1090 GD, The Netherlands
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4
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Hunt NT. Using 2D-IR Spectroscopy to Measure the Structure, Dynamics, and Intermolecular Interactions of Proteins in H 2O. Acc Chem Res 2024; 57:685-692. [PMID: 38364823 PMCID: PMC10918835 DOI: 10.1021/acs.accounts.3c00682] [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] [Received: 10/30/2023] [Revised: 01/30/2024] [Accepted: 01/30/2024] [Indexed: 02/18/2024]
Abstract
Infrared (IR) spectroscopy probes molecular structure at the level of the chemical bond or functional group. In the case of proteins, the most informative band in the IR spectrum is the amide I band, which arises predominantly from the C═O stretching vibration of the peptide link. The folding of proteins into secondary and tertiary structures leads to vibrational coupling between peptide units, generating specific amide I spectral signatures that provide a fingerprint of the macromolecular conformation. Ultrafast two-dimensional IR (2D-IR) spectroscopy allows the amide I band of a protein to be spread over a second frequency dimension in a way that mirrors 2D-NMR methods. This means that amide I 2D-IR spectroscopy produces a spectral map that is exquisitely sensitive to protein structure and dynamics and so provides detailed insights that cannot be matched by IR absorption spectroscopy. As a result, 2D-IR spectroscopy has emerged as a powerful tool for probing protein structure and dynamics over a broad range of time and length scales in the solution phase at room temperature. However, the protein amide I band coincides with an IR absorption from the bending vibration of water (δHOH), the natural biological solvent. To circumvent this problem, protein IR studies are routinely performed in D2O solutions because H/D substitution shifts the solvent bending mode (δDOD) to a lower frequency, revealing the amide I band. While effective, this method raises fundamental questions regarding the impact of the change in solvent mass on the structural or solvation dynamics of the protein and the removal of the energetic resonance between solvent and solute.In this Account, a series of studies applying 2D-IR to study the spectroscopy and dynamics of proteins in H2O-rich solvents is reviewed. A comparison of IR absorption spectroscopy and 2D-IR spectroscopy of protein-containing fluids is used to demonstrate the basis of the approach before a series of applications is presented. These range from measurements of fundamental protein biophysics to recent applications of machine learning to gain insight into protein-drug binding in complex mixtures. An outlook is presented, considering the potential for 2D-IR measurements to contribute to our understanding of protein behavior under near-physiological conditions, along with an evaluation of the obstacles that still need to be overcome.
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Affiliation(s)
- Neil T. Hunt
- Department of Chemistry and York Biomedical
Research Institute, University of York, Heslington, York, YO10
5DD, U.K.
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5
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Hunt NT. Biomolecular infrared spectroscopy: making time for dynamics. Chem Sci 2024; 15:414-430. [PMID: 38179520 PMCID: PMC10763549 DOI: 10.1039/d3sc05223k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 11/24/2023] [Indexed: 01/06/2024] Open
Abstract
Time resolved infrared spectroscopy of biological molecules has provided a wealth of information relating to structural dynamics, conformational changes, solvation and intermolecular interactions. Challenges still exist however arising from the wide range of timescales over which biological processes occur, stretching from picoseconds to minutes or hours. Experimental methods are often limited by vibrational lifetimes of probe groups, which are typically on the order of picoseconds, while measuring an evolving system continuously over some 18 orders of magnitude in time presents a raft of technological hurdles. In this Perspective, a series of recent advances which allow biological molecules and processes to be studied over an increasing range of timescales, while maintaining ultrafast time resolution, will be reviewed, showing that the potential for real-time observation of biomolecular function draws ever closer, while offering a new set of challenges to be overcome.
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Affiliation(s)
- Neil T Hunt
- Department of Chemistry and York Biomedical Research Institute, University of York Heslington York YO10 5DD UK
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6
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Giubertoni G, Bonn M, Woutersen S. D 2O as an Imperfect Replacement for H 2O: Problem or Opportunity for Protein Research? J Phys Chem B 2023; 127:8086-8094. [PMID: 37722111 PMCID: PMC10544019 DOI: 10.1021/acs.jpcb.3c04385] [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: 06/29/2023] [Revised: 08/28/2023] [Indexed: 09/20/2023]
Abstract
D2O is commonly used as a solvent instead of H2O in spectroscopic studies of proteins, in particular, in infrared and nuclear-magnetic-resonance spectroscopy. D2O is chemically equivalent to H2O, and the differences, particularly in hydrogen-bond strength, are often ignored. However, replacing solvent water with D2O can affect not only the kinetics but also the structure and stability of biomolecules. Recent experiments have shown that even the mesoscopic structures and the elastic properties of biomolecular assemblies, such as amyloids and protein networks, can be very different in D2O and H2O. We discuss these findings, which probably are just the tip of the iceberg, and which seem to call for obtaining a better understanding of the H2O/D2O-isotope effect on water-water and water-protein interactions. Such improved understanding may change the differences between H2O and D2O as biomolecular solvents from an elephant in the room to an opportunity for protein research.
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Affiliation(s)
- Giulia Giubertoni
- Van
’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands
| | - Mischa Bonn
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Sander Woutersen
- Van
’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098XH Amsterdam, The Netherlands
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7
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Zheng X, Yang N, Hou Y, Cai K. Dissecting amide-I vibrations in histidine dipeptide. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 292:122424. [PMID: 36750008 DOI: 10.1016/j.saa.2023.122424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 01/27/2023] [Accepted: 01/28/2023] [Indexed: 06/18/2023]
Abstract
The amide-I vibrational characteristics and conformational preferences of the model compound - histidine dipeptide (Ac-His-NHCH3, HISD) in gas phase and solution have been revealed with the help of ab initio calculations and wavefunction analyses. The Gibbs free energy surfaces (FESs) of solvated HISD were smoothed by solvent effect to exhibit different structural populations concerning various external environments. It was shown that the most stable conformations of HISD in CHCl3 and gas phase are C7eq, while those in DMSO and water are β and PPII, respectively. Compared with ALAD, the number of accessible conformational states on these FESs was predicted to be reduced due to the steric effect of imidazole group. The two amide-I normal modes of HISD were found to have intrinsically secondary structural dependencies, and be sensitive to surrounding environments. The average amide-Ia frequencies of HISD isomers in these environments were predicted to be almost the same as those of ALAD, while the amide-Ib mean frequencies were estimated to be lower than ALAD due to the intramolecular interactions between the imidazole group and amino-terminal amide unit. The good linear correlations between amide-I frequencies and the atomic electrostatic potentials (ESPs) of amide groups were also found to interpret the solvent-induced amide-I frequency shifts of HISD at the electronic structure level. These results allow us to gain a deep understanding of amide-I vibrations of HISD, and would be helpful for the site-specific conformational monitoring and spectral interpretation of solvated polypeptides.
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Affiliation(s)
- Xuan Zheng
- College of Chemistry, Chemical Engineering and Environment, Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Fujian Provincial Key Laboratory of Pollution Monitoring and Control, Minnan Normal University, Zhangzhou 363000, PR China.
| | - Nairong Yang
- College of Chemistry, Chemical Engineering and Environment, Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Fujian Provincial Key Laboratory of Pollution Monitoring and Control, Minnan Normal University, Zhangzhou 363000, PR China
| | - Yanjun Hou
- College of Chemistry, Chemical Engineering and Environment, Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Fujian Provincial Key Laboratory of Pollution Monitoring and Control, Minnan Normal University, Zhangzhou 363000, PR China
| | - Kaicong Cai
- College of Chemistry and Materials Science, Fujian Provincial Key Laboratory of Advanced Materials Oriented Chemical Engineering, Fujian Normal University, Fuzhou 350007, PR China; Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Xiamen 361005, PR China; Fujian Provincial Key Laboratory of Featured Biochemical and Chemical Materials, Ningde Normal University, Ningde 352100, PR China.
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8
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Choi S, Chun SY, Kwak K, Cho M. Micro-Raman spectroscopic analysis of liquid-liquid phase separation. Phys Chem Chem Phys 2023; 25:9051-9060. [PMID: 36843414 DOI: 10.1039/d2cp05115j] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Liquid-liquid phase separation (LLPS) plays a significant role in various biological processes, including the formation of membraneless organelles and pathological protein aggregation. Although many studies have found various factors that modulate the LLPS process or the liquid-to-solid phase transition (LSPT) using microscopy or fluorescence-based methods, the molecular mechanistic details underlying LLPS and protein aggregation within liquid droplets remain uncharacterized. Therefore, structural information on proteins inside liquid droplets is required to understand the mechanistic link to amyloid formation. In the present study, we monitored droplet formation related to protein fibrillation using micro-Raman spectroscopy in combination with differential interference contrast (DIC) microscopy to study the conformational change in proteins and the hydrogen-bonding (H-bonding) structure of water during LLPS. Interestingly, we found that the O-D stretching band for water (HOD in H2O) inside the droplets exhibited a distinct Raman spectrum from that of the bulk water, suggesting that the time-dependent change in the hydration environment in the protein droplets during the process of LLPS can be studied. These results demonstrate that the superior spatial resolution of micro-Raman spectroscopy offers significant advantages in investigating the molecular mechanisms of LLPS and following LSPT processes.
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Affiliation(s)
- Suin Choi
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Republic of Korea.,Department of Chemistry, Korea University, Seoul 02841, Republic of Korea.
| | - So Yeon Chun
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Republic of Korea.,Department of Chemistry, Korea University, Seoul 02841, Republic of Korea.
| | - Kyungwon Kwak
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Republic of Korea.,Department of Chemistry, Korea University, Seoul 02841, Republic of Korea.
| | - Minhaeng Cho
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Seoul 02841, Republic of Korea.,Department of Chemistry, Korea University, Seoul 02841, Republic of Korea.
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9
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Li X, Guan J, Shen C, Yu Z, Zheng J. Direct observation of conformations of a high-mobility n-type low-bandgap copolymer in solutions and solid films. J Chem Phys 2023; 158:064202. [PMID: 36792510 DOI: 10.1063/5.0134807] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The aggregation morphologies of conjugated polymers in solutions and solid films are important for their optoelectronic applications. Due to the amorphous state of the polymers, it remains a great challenge to determine their conformations in either liquids or solids. Herein, a ps/fs synchronized 2D IR technique is applied to investigate the molecular conformations of a high-mobility n-type low-bandgap copolymer, N2200, dissolved in CHCl3 and CCl4, and in solid films cast from both solutions by the vibrational cross-angle method. In CCl4, the polymer forms more aggregates and folds more and the backbone dihedral angle of C-C(NDI)/C-S(Thiophene) of its average conformation is about 10° more distorted than that in CHCl3 and the most stable conformation for a free molecule. Anti-intuitively, the solid films cast from both solutions have the same molecular conformation, and the conformation is similar to that of the polar CHCl3 rather than the conformation of the less polar CCl4. The results imply that the interaction between the polymer backbones is probably stronger than its interaction with CCl4, which can naturally guide the rearrangement of polymer chains during the evaporation of solvent molecules. This work also implies that the balance and competition between the polymer/polymer interaction and the polymer/solvent interaction seem to be the dominant factors responsible for what morphology can form in a solid film cast from solution. It is not always true that different molecular conformations must exist in solid films grown from different solutions with different polarity or different extents of aggregates with different conformations.
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Affiliation(s)
- Xinmao Li
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
| | - Jianxin Guan
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
| | - Chengzhen Shen
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
| | - Zhihao Yu
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
| | - Junrong Zheng
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
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10
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Rutherford SH, Baker MJ, Hunt NT. 2D-IR spectroscopy of proteins in H 2O-A Perspective. J Chem Phys 2023; 158:030901. [PMID: 36681646 DOI: 10.1063/5.0129480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The form of the amide I infrared absorption band provides a sensitive probe of the secondary structure and dynamics of proteins in the solution phase. However, the frequency coincidence of the amide I band with the bending vibrational mode of H2O has necessitated the widespread use of deuterated solvents. Recently, it has been demonstrated that ultrafast 2D-IR spectroscopy allows the detection of the protein amide I band in H2O-based fluids, meaning that IR methods can now be applied to study proteins in physiologically relevant solvents. In this perspective, we describe the basis of the 2D-IR method for observing the protein amide I band in H2O and show how this development has the potential to impact areas ranging from our fundamental appreciation of protein structural dynamics to new applications for 2D-IR spectroscopy in the analytical and biomedical sciences. In addition, we discuss how the spectral response of water, rather than being a hindrance, now provides a basis for new approaches to data pre-processing, standardization of 2D-IR data collection, and signal quantification. Ultimately, we visualize a direction of travel toward the creation of 2D-IR spectral libraries that can be linked to advanced computational methods for use in high-throughput protein screening and disease diagnosis.
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Affiliation(s)
- Samantha H Rutherford
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Technology and Innovation Centre, 99 George Street, Glasgow G1 1RD, United Kingdom
| | - Matthew J Baker
- School of Medicine, Faculty of Clinical Biomedical Sciences, University of Central Lancashire, Preston PR1 2HE, United Kingdom
| | - Neil T Hunt
- Department of Chemistry and York Biomedical Research Institute, University of York, York YO10 5DD, United Kingdom
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11
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Giubertoni G, Rombouts G, Caporaletti F, Deblais A, van Diest R, Reek JNH, Bonn D, Woutersen S. Infrared Diffusion-Ordered Spectroscopy Reveals Molecular Size and Structure. Angew Chem Int Ed Engl 2023; 62:e202213424. [PMID: 36259515 PMCID: PMC10107201 DOI: 10.1002/anie.202213424] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Indexed: 11/07/2022]
Abstract
Inspired by ideas from NMR, we have developed Infrared Diffusion-Ordered Spectroscopy (IR-DOSY), which simultaneously characterizes molecular structure and size. We rely on the fact that the diffusion coefficient of a molecule is determined by its size through the Stokes-Einstein relation, and achieve sensitivity to the diffusion coefficient by creating a concentration gradient and tracking its equilibration in an IR-frequency resolved manner. Analogous to NMR-DOSY, a two-dimensional IR-DOSY spectrum has IR frequency along one axis and diffusion coefficient (or equivalently, size) along the other, so the chemical structure and the size of a compound are characterized simultaneously. In an IR-DOSY spectrum of a mixture, molecules with different sizes are nicely separated into distinct sets of IR peaks. Extending this idea to higher dimensions, we also perform 3D-IR-DOSY, in which we combine the conformation sensitivity of femtosecond multi-dimensional IR spectroscopy with size sensitivity.
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Affiliation(s)
- Giulia Giubertoni
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098XH, Amsterdam, The Netherlands
| | - Gijs Rombouts
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098XH, Amsterdam, The Netherlands
| | - Federico Caporaletti
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098XH, Amsterdam, The Netherlands.,Institute of Physics, University of Amsterdam, Science Park 904, 1098XH, Amsterdam, The Netherlands
| | - Antoine Deblais
- Institute of Physics, University of Amsterdam, Science Park 904, 1098XH, Amsterdam, The Netherlands
| | - Rianne van Diest
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098XH, Amsterdam, The Netherlands
| | - Joost N H Reek
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098XH, Amsterdam, The Netherlands
| | - Daniel Bonn
- Institute of Physics, University of Amsterdam, Science Park 904, 1098XH, Amsterdam, The Netherlands
| | - Sander Woutersen
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098XH, Amsterdam, The Netherlands
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