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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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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3
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Ma Z, Chen L, Xu C, Fournier JA. Two-Dimensional Infrared Spectroscopy of Isolated Molecular Ions. J Phys Chem Lett 2023; 14:9683-9689. [PMID: 37871134 DOI: 10.1021/acs.jpclett.3c02661] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Two-dimensional infrared (2D IR) spectroscopy of mass-selected, cryogenically cooled molecular ions is presented. Nonlinear response pathways, encoded in the time-domain photodissociation action response of weakly bound N2 messenger tags, were isolated using pulse shaping techniques following excitation with four collinear ultrafast IR pulses. 2D IR spectra of Re(CO)3(CH3CN)3+ ions capture off-diagonal cross-peak bleach signals between the asymmetric and symmetric carbonyl stretching transitions. These cross peaks display intensity variations as a function of pump-probe delay time due to coherent coupling between the vibrational modes. Well-resolved 2D IR features in the congested fingerprint region of protonated caffeine (C8H10N4O2H+) are also reported. Importantly, intense cross-peak signals were observed at 3 ps waiting time, indicating that tag-loss dynamics are not competing with the measured nonlinear signals. These demonstrations pave the way for more precise studies of molecular interactions and dynamics that are not easily obtainable with current condensed-phase methodologies.
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Affiliation(s)
- Zifan Ma
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Liangyi Chen
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Chuzhi Xu
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Joseph A Fournier
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130, United States
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4
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Webb KR, Hess KA, Shmidt A, Segner KD, Buchanan LE. Probing local changes to α-helical structures with 2D IR spectroscopy and isotope labeling. Biophys J 2023; 122:1491-1502. [PMID: 36906800 PMCID: PMC10147839 DOI: 10.1016/j.bpj.2023.03.014] [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: 05/24/2022] [Revised: 10/13/2022] [Accepted: 03/08/2023] [Indexed: 03/12/2023] Open
Abstract
α-Helical secondary structures impart specific mechanical and physiochemical properties to peptides and proteins, enabling them to perform a vast array of molecular tasks ranging from membrane insertion to molecular allostery. Loss of α-helical content in specific regions can inhibit native protein function or induce new, potentially toxic, biological activities. Thus, identifying specific residues that exhibit loss or gain of helicity is critical for understanding the molecular basis of function. Two-dimensional infrared (2D IR) spectroscopy coupled with isotope labeling is capable of capturing detailed structural changes in polypeptides. Yet, questions remain regarding the inherent sensitivity of isotope-labeled modes to local changes in α-helicity, such as terminal fraying; the origin of spectral shifts (hydrogen-bonding versus vibrational coupling); and the ability to definitively detect coupled isotopic signals in the presence of overlapping side chains. Here, we address each of these points individually by characterizing a short, model α-helix (DPAEAAKAAAGR-NH2) with 2D IR and isotope labeling. These results demonstrate that pairs of 13C18O probes placed three residues apart can detect subtle structural changes and variations along the length of the model peptide as the α-helicity is systematically tuned. Comparison of singly and doubly labeled peptides affirm that frequency shifts arise primarily from hydrogen-bonding, while vibrational coupling between paired isotopes leads to increased peak areas that can be clearly differentiated from underlying side-chain modes or uncoupled isotope labels not participating in helical structures. These results demonstrate that 2D IR in tandem with i,i+3 isotope-labeling schemes can capture residue-specific molecular interactions within a single turn of an α-helix.
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Affiliation(s)
| | - Kayla Anne Hess
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee
| | - Alisa Shmidt
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee
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5
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Hess KA, Spear NJ, Vogelsang SA, Macdonald JE, Buchanan LE. Determining the impact of gold nanoparticles on amyloid aggregation with 2D IR spectroscopy. J Chem Phys 2023; 158:091101. [PMID: 36889961 PMCID: PMC9981241 DOI: 10.1063/5.0136376] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023] Open
Abstract
As nanomaterials become more prevalent in both industry and medicine, it is crucial to fully understand their health risks. One area of concern is the interaction of nanoparticles with proteins, including their ability to modulate the uncontrolled aggregation of amyloid proteins associated with diseases, such as Alzheimer's disease and type II diabetes, and potentially extend the lifetime of cytotoxic soluble oligomers. This work demonstrates that two-dimensional infrared spectroscopy and 13C18O isotope labeling can be used to follow the aggregation of human islet amyloid polypeptide (hIAPP) in the presence of gold nanoparticles (AuNPs) with single-residue structural resolution. 60 nm AuNPs were found to inhibit hIAPP, tripling the aggregation time. Furthermore, calculating the actual transition dipole strength of the backbone amide I' mode reveals that hIAPP forms a more ordered aggregate structure in the presence of AuNPs. Ultimately, such studies can provide insight into how mechanisms of amyloid aggregation are altered in the presence of nanoparticles, furthering our understanding of protein-nanoparticle interactions.
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Affiliation(s)
- Kayla A Hess
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Lane, Nashville, Tennessee 37235, USA
| | - Nathan J Spear
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Lane, Nashville, Tennessee 37235, USA
| | - Sophia A Vogelsang
- Department of Chemistry, Vanderbilt University, 1234 Stevenson Center Lane, Nashville, Tennessee 37235, USA
| | - Janet E Macdonald
- 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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6
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Tumbic GW, Hossan MY, Thielges MC. Protein Dynamics by Two-Dimensional Infrared Spectroscopy. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2021; 14:299-321. [PMID: 34314221 PMCID: PMC8713465 DOI: 10.1146/annurev-anchem-091520-091009] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Proteins function as ensembles of interconverting structures. The motions span from picosecond bond rotations to millisecond and longer subunit displacements. Characterization of functional dynamics on all spatial and temporal scales remains challenging experimentally. Two-dimensional infrared spectroscopy (2D IR) is maturing as a powerful approach for investigating proteins and their dynamics. We outline the advantages of IR spectroscopy, describe 2D IR and the information it provides, and introduce vibrational groups for protein analysis. We highlight example studies that illustrate the power and versatility of 2D IR for characterizing protein dynamics and conclude with a brief discussion of the outlook for biomolecular 2D IR.
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Affiliation(s)
- Goran W Tumbic
- Department of Chemistry, Indiana University, Bloomington, Indiana 47401, USA;
| | - Md Yeathad Hossan
- Department of Chemistry, Indiana University, Bloomington, Indiana 47401, USA;
| | - Megan C Thielges
- Department of Chemistry, Indiana University, Bloomington, Indiana 47401, USA;
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7
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Linear and Non-Linear Middle Infrared Spectra of Penicillin G in the CO Stretching Mode Region. Symmetry (Basel) 2021. [DOI: 10.3390/sym13010106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In this work we report the linear and non-linear IR spectral response characterization of the CO bonds of PenicillinG sodium salt in D2O and in DMSO−d6 solutions. In order to better characterize the spectral IR features in the CO stretching region, broadband middle infrared pump-probe spectra are recorded. The role of hydrogen bonds in determining the inhomogeneous broadening and in tuning anharmonicity of the different types of oscillators is exploited. Narrow band pump experiments, at the three central frequencies of β−lactam, amide and carboxylate CO stretching modes, identify the couplings between the different types of CO oscillators opening the possibility to gather structural dynamic information. Our results show that the strongest coupling is between the β−lactam and the carboxylate CO vibrational modes.
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8
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Minnes L, Greetham GM, Shaw DJ, Clark IP, Fritzsch R, Towrie M, Parker AW, Henry AJ, Taylor RJ, Hunt NT. Uncovering the Early Stages of Domain Melting in Calmodulin with Ultrafast Temperature-Jump Infrared Spectroscopy. J Phys Chem B 2019; 123:8733-8739. [PMID: 31557034 PMCID: PMC7007250 DOI: 10.1021/acs.jpcb.9b08870] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
![]()
The signaling protein
calmodulin (CaM) undergoes a well-known change
in secondary structure upon binding Ca2+, but the structural
plasticity of the Ca2+-free apo state
is linked to CaM functionality. Variable temperature studies of apo-CaM indicate two structural transitions at 46 and 58
°C that are assigned to melting of the C- and N-terminal domains,
respectively, but the molecular mechanism of domain unfolding is unknown.
We report temperature-jump time-resolved infrared (IR) spectroscopy
experiments designed to target the first steps in the C-terminal domain
melting transition of human apo-CaM. A comparison
of the nonequilibrium relaxation of apo-CaM with
the more thermodynamically stable holo-CaM, with
4 equiv of Ca2+ bound, shows that domain melting of apo-CaM begins on microsecond time scales with α-helix
destabilization. These observations enable the assignment of previously
reported dynamics of CaM on hundreds of microsecond time scales to
thermally activated melting, producing a complete mechanism for thermal
unfolding of CaM.
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Affiliation(s)
- Lucy Minnes
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , United Kingdom
| | - Gregory M Greetham
- STFC Central Laser Facility, Research Complex at Harwell , Rutherford Appleton Laboratory , Harwell Campus , Didcot OX11 0QX , United Kingdom
| | | | - Ian P Clark
- STFC Central Laser Facility, Research Complex at Harwell , Rutherford Appleton Laboratory , Harwell Campus , Didcot OX11 0QX , United Kingdom
| | - Robby Fritzsch
- Department of Physics, SUPA , University of Strathclyde , Glasgow G4 0NG , United Kingdom
| | - Michael Towrie
- STFC Central Laser Facility, Research Complex at Harwell , Rutherford Appleton Laboratory , Harwell Campus , Didcot OX11 0QX , United Kingdom
| | - Anthony W Parker
- STFC Central Laser Facility, Research Complex at Harwell , Rutherford Appleton Laboratory , Harwell Campus , Didcot OX11 0QX , United Kingdom
| | | | | | - Neil T Hunt
- Department of Chemistry and York Biomedical Research Institute , University of York , Heslington, York YO10 5DD , United Kingdom
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9
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Ramos S, Thielges MC. Site-Specific 1D and 2D IR Spectroscopy to Characterize the Conformations and Dynamics of Protein Molecular Recognition. J Phys Chem B 2019; 123:3551-3566. [PMID: 30848912 DOI: 10.1021/acs.jpcb.9b00969] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Proteins exist as ensembles of interconverting states on a complex energy landscape. A complete, molecular-level understanding of their function requires knowledge of the populated states and thus the experimental tools to characterize them. Infrared (IR) spectroscopy has an inherently fast time scale that can capture all states and their dynamics with, in principle, bond-specific spatial resolution, and 2D IR methods that provide richer information are becoming more routine. Although application of IR spectroscopy for investigation of proteins is challenged by spectral congestion, the issue can be overcome by site-specific introduction of amino acid side chains that have IR probe groups with frequency-resolved absorptions, which furthermore enables selective characterization of different locations in proteins. Here, we briefly introduce the biophysical methods and summarize the current progress toward the study of proteins. We then describe our efforts to apply site-specific 1D and 2D IR spectroscopy toward elucidation of protein conformations and dynamics to investigate their involvement in protein molecular recognition, in particular mediated by dynamic complexes: plastocyanin and its binding partner cytochrome f, cytochrome P450s and substrates or redox partners, and Src homology 3 domains and proline-rich peptide motifs. We highlight the advantages of frequency-resolved probes to characterize specific, local sites in proteins and uncover variation among different locations, as well as the advantage of the fast time scale of IR spectroscopy to detect rapidly interconverting states. In addition, we illustrate the greater insight provided by 2D methods and discuss potential routes for further advancement of the field of biomolecular 2D IR spectroscopy.
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Affiliation(s)
- Sashary Ramos
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Megan C Thielges
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
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10
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Vibrational Approach to the Dynamics and Structure of Protein Amyloids. Molecules 2019; 24:molecules24010186. [PMID: 30621325 PMCID: PMC6337179 DOI: 10.3390/molecules24010186] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 12/31/2018] [Accepted: 01/02/2019] [Indexed: 02/06/2023] Open
Abstract
Amyloid diseases, including neurodegenerative diseases such as Alzheimer’s and Parkinson’s, are linked to a poorly understood progression of protein misfolding and aggregation events that culminate in tissue-selective deposition and human pathology. Elucidation of the mechanistic details of protein aggregation and the structural features of the aggregates is critical for a comprehensive understanding of the mechanisms of protein oligomerization and fibrillization. Vibrational spectroscopies, such as Fourier transform infrared (FTIR) and Raman, are powerful tools that are sensitive to the secondary structure of proteins and have been widely used to investigate protein misfolding and aggregation. We address the application of the vibrational approaches in recent studies of conformational dynamics and structural characteristics of protein oligomers and amyloid fibrils. In particular, introduction of isotope labelled carbonyl into a peptide backbone, and incorporation of the extrinsic unnatural amino acids with vibrational moieties on the side chain, have greatly expanded the ability of vibrational spectroscopy to obtain site-specific structural and dynamic information. The applications of these methods in recent studies of protein aggregation are also reviewed.
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11
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Hogle DG, Cunningham AR, Tucker MJ. Equilibrium versus Nonequilibrium Peptide Dynamics: Insights into Transient 2D IR Spectroscopy. J Phys Chem B 2018; 122:8783-8795. [PMID: 30040900 DOI: 10.1021/acs.jpcb.8b05063] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Over the past two decades, two-dimensional infrared (2D IR) spectroscopy has evolved from the theoretical underpinnings of nonlinear spectroscopy as a means of investigating detailed molecular structure on an ultrafast time scale. The combined time and spectral resolution over which spectra can be collected on complex molecular systems has led to the precise structural resolution of dynamic species that have previously been impossible to directly observe through traditional methods. The adoption of 2D IR spectroscopy for the study of protein folding and peptide interactions has provided key details of how small changes in conformations can exert major influences on the activities of these complex molecular systems. Traditional 2D IR experiments are limited to molecules under equilibrium conditions, where small motions and fluctuations of these larger molecules often still lead to functionality. Utilizing techniques that allow the rapid initiation of chemical or structural changes in conjunction with 2D IR spectroscopy, i.e., transient 2D IR, a vast dynamic range becomes available to the spectroscopist uncovering structural content far from equilibrium. Furthermore, this allows the observation of reaction pathways of these macromolecules under quasi- and nonequilibrium conditions.
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Affiliation(s)
- David G Hogle
- Department of Chemistry , University of Nevada, Reno , 1664 North Virginia Street , Reno , Nevada 89557 , United States
| | - Amy R Cunningham
- Department of Chemistry , University of Nevada, Reno , 1664 North Virginia Street , Reno , Nevada 89557 , United States
| | - Matthew J Tucker
- Department of Chemistry , University of Nevada, Reno , 1664 North Virginia Street , Reno , Nevada 89557 , United States
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12
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Maj M, Lomont JP, Rich KL, Alperstein AM, Zanni MT. Site-specific detection of protein secondary structure using 2D IR dihedral indexing: a proposed assembly mechanism of oligomeric hIAPP. Chem Sci 2018; 9:463-474. [PMID: 29619202 PMCID: PMC5868010 DOI: 10.1039/c7sc03789a] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 11/02/2017] [Indexed: 12/19/2022] Open
Abstract
Human islet amyloid polypeptide (hIAPP) aggregates into fibrils through oligomers that have been postulated to contain α-helices as well as β-sheets. We employ a site-specific isotope labeling strategy that is capable of detecting changes in dihedral angles when used in conjunction with 2D IR spectroscopy. The method is analogous to the chemical shift index used in NMR spectroscopy for assigning protein secondary structure. We introduce isotope labels at two neighbouring residues, which results in an increased intensity and positive frequency shift if those residues are α-helical versus a negative frequency shift in β-sheets and turns. The 2D IR dihedral index approach is demonstrated for hIAPP in micelles for which the polypeptide structure is known, using pairs of 13C18O isotope labels L12A13 and L16V17, along with single labeled control experiments. Applying the approach to aggregation experiments performed in buffer, we show that about 27-38% of hIAPP peptides adopt an α-helix secondary structure in the monomeric state at L12A13, prior to aggregation, but not at L16V17 residues. At L16V17, the kinetics are described solely by the monomer and fiber conformations, but at L12A13 the kinetics exhibit a third state that is created by an oligomeric intermediate. Control experiments performed with a single isotope label at A13 exhibit two-state kinetics, indicating that a previously unknown change in dihedral angle occurs at L12A13 as hIAPP transitions from the intermediate to fiber structures. We propose a mechanism for aggregation, in which helices seed oligomer formation via structures analogous to leucine rich repeat proteins.
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Affiliation(s)
- Michał Maj
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706-1396 , USA .
| | - Justin P Lomont
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706-1396 , USA .
| | - Kacie L Rich
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706-1396 , USA .
| | - Ariel M Alperstein
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706-1396 , USA .
| | - Martin T Zanni
- Department of Chemistry , University of Wisconsin-Madison , Madison , Wisconsin 53706-1396 , USA .
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13
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Fábri C, Albert S, Chen Z, Prentner R, Quack M. A molecular quantum switch based on tunneling in meta-d-phenol C6H4DOH. Phys Chem Chem Phys 2018; 20:7387-7394. [DOI: 10.1039/c8cp00133b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The concept of a molecular quantum switch is introduced from realistic, quantitative wavepacket analyses of tunneling switching in m-d-phenol.
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Affiliation(s)
- Csaba Fábri
- Laboratory of Molecular Structure and Dynamics
- Institute of Chemistry
- Eötvös University
- H-1117 Budapest
- Hungary
| | | | - Ziqiu Chen
- Physical Chemistry
- ETH Zürich
- CH-8093 Zürich
- Switzerland
| | | | - Martin Quack
- Physical Chemistry
- ETH Zürich
- CH-8093 Zürich
- Switzerland
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14
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Minnes L, Shaw DJ, Cossins BP, Donaldson PM, Greetham GM, Towrie M, Parker AW, Baker MJ, Henry AJ, Taylor RJ, Hunt NT. Quantifying Secondary Structure Changes in Calmodulin Using 2D-IR Spectroscopy. Anal Chem 2017; 89:10898-10906. [DOI: 10.1021/acs.analchem.7b02610] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Lucy Minnes
- Department
of Physics, University of Strathclyde, SUPA, 107 Rottenrow East, Glasgow, G4 0NG, United Kingdom
| | | | | | - Paul M. Donaldson
- STFC
Central Laser Facility, Research Complex at Harwell, Rutherford Appleton
Laboratory, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX, United Kingdom
| | - Gregory M. Greetham
- STFC
Central Laser Facility, Research Complex at Harwell, Rutherford Appleton
Laboratory, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX, United Kingdom
| | - Michael Towrie
- STFC
Central Laser Facility, Research Complex at Harwell, Rutherford Appleton
Laboratory, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX, United Kingdom
| | - Anthony W. Parker
- STFC
Central Laser Facility, Research Complex at Harwell, Rutherford Appleton
Laboratory, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX, United Kingdom
| | - Matthew J. Baker
- WestCHEM,
Department of Pure and Applied Chemistry, Technology and Innovation
Centre, University of Strathclyde, 99 George Street, Glasgow, G1 1RD, United Kingdom
| | | | | | - Neil T. Hunt
- Department
of Physics, University of Strathclyde, SUPA, 107 Rottenrow East, Glasgow, G4 0NG, United Kingdom
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15
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Rodgers JM, Zhang W, Bazewicz CG, Chen J, Brewer SH, Gai F. Kinetic Isotope Effect Provides Insight into the Vibrational Relaxation Mechanism of Aromatic Molecules: Application to Cyano-phenylalanine. J Phys Chem Lett 2016; 7:1281-1287. [PMID: 26990401 PMCID: PMC4824650 DOI: 10.1021/acs.jpclett.6b00325] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Varying the reduced mass of an oscillator via isotopic substitution provides a convenient means to alter its vibrational frequency and hence has found wide applications. Herein, we show that this method can also help delineate the vibrational relaxation mechanism, using four isotopomers of the unnatural amino acid p-cyano-phenylalanine (Phe-CN) as models. In water, the nitrile stretching frequencies of these isotopomers, Phe-(12)C(14)N (1), Phe-(12)C(15)N (2), Phe-(13)C(14)N (3), and Phe-(13)C(15)N (4), are found to be equally separated by ∼27 cm(-1), whereas their vibrational lifetimes are determined to be 4.0 ± 0.2 (1), 2.2 ± 0.1 (2), 3.4 ± 0.2 (3), and 7.9 ± 0.5 ps (4), respectively. We find that an empirical relationship that considers the effective reduced mass of CN can accurately account for the observed frequency gaps, while the vibrational lifetime distribution, which suggests an intramolecular relaxation mechanism, can be rationalized by the order-specific density of states near the CN stretching frequency.
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Affiliation(s)
- Jeffrey M. Rodgers
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
| | - Wenkai Zhang
- The Ultrafast Optical Processes Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
| | | | - Jianxin Chen
- The Ultrafast Optical Processes Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
| | - Scott H. Brewer
- Department of Chemistry, Franklin & Marshall College, Lancaster, Pennsylvania 17604-3003
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
- The Ultrafast Optical Processes Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
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16
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Bakulin AA, Silva C, Vella E. Ultrafast Spectroscopy with Photocurrent Detection: Watching Excitonic Optoelectronic Systems at Work. J Phys Chem Lett 2016; 7:250-8. [PMID: 26711855 PMCID: PMC4819534 DOI: 10.1021/acs.jpclett.5b01955] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 12/29/2015] [Indexed: 05/22/2023]
Abstract
While ultrafast spectroscopy with photocurrent detection was almost unknown before 2012, in the last 3 years, a number of research groups from different fields have independently developed ultrafast electric probe approaches and reported promising pilot studies. Here, we discuss these recent advances and provide our perspective on how photocurrent detection successfully overcomes many limitations of all-optical methods, which makes it a technique of choice when device photophysics is concerned. We also highlight compelling existing problems and research questions and suggest ways for further development, outlining the potential breakthroughs to be expected in the near future using photocurrent ultrafast optical probes.
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Affiliation(s)
- Artem A. Bakulin
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
| | - Carlos Silva
- Département de physique & Regroupement
québécois sur les matériaux de pointe, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal, Québec H3C 3J7, Canada
| | - Eleonora Vella
- Département de physique & Regroupement
québécois sur les matériaux de pointe, Université de Montréal, C.P. 6128, Succursale centre-ville, Montréal, Québec H3C 3J7, Canada
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17
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Affiliation(s)
- Juan Zhao
- Beijing
National Laboratory
for Molecular Sciences; Laboratory of Molecular Reaction Dynamics,
Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Jianping Wang
- Beijing
National Laboratory
for Molecular Sciences; Laboratory of Molecular Reaction Dynamics,
Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
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18
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Abstract
Infrared spectroscopy has played an instrumental role in the study of a wide variety of biological questions. However, in many cases, it is impossible or difficult to rely on the intrinsic vibrational modes of biological molecules of interest, such as proteins, to reveal structural and environmental information in a site-specific manner. To overcome this limitation, investigators have dedicated many recent efforts to the development and application of various extrinsic vibrational probes that can be incorporated into biological molecules and used to site-specifically interrogate their structural or environmental properties. In this review, we highlight recent advancements in this rapidly growing research area.
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19
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Marty R, Frauenrath H, Helbing J. Aggregates from Perylene Bisimide Oligopeptides as a Test Case for Giant Vibrational Circular Dichroism. J Phys Chem B 2014; 118:11152-60. [DOI: 10.1021/jp506837c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Roman Marty
- Institute
of Materials, Ecole Polytechnique Federale de Lausanne (EPFL), EPFL - STI - IMX - LMOM, MXG 037, Station 12, 1015 Lausanne, Switzerland
| | - Holger Frauenrath
- Institute
of Materials, Ecole Polytechnique Federale de Lausanne (EPFL), EPFL - STI - IMX - LMOM, MXG 037, Station 12, 1015 Lausanne, Switzerland
| | - Jan Helbing
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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20
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Ghosh A, Wang J, Moroz YS, Korendovych IV, Zanni M, DeGrado WF, Gai F, Hochstrasser RM. 2D IR spectroscopy reveals the role of water in the binding of channel-blocking drugs to the influenza M2 channel. J Chem Phys 2014; 140:235105. [PMID: 24952572 PMCID: PMC4098053 DOI: 10.1063/1.4881188] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 05/21/2014] [Indexed: 12/21/2022] Open
Abstract
Water is an integral part of the homotetrameric M2 proton channel of the influenza A virus, which not only assists proton conduction but could also play an important role in stabilizing channel-blocking drugs. Herein, we employ two dimensional infrared (2D IR) spectroscopy and site-specific IR probes, i.e., the amide I bands arising from isotopically labeled Ala30 and Gly34 residues, to probe how binding of either rimantadine or 7,7-spiran amine affects the water dynamics inside the M2 channel. Our results show, at neutral pH where the channel is non-conducting, that drug binding leads to a significant increase in the mobility of the channel water. A similar trend is also observed at pH 5.0 although the difference becomes smaller. Taken together, these results indicate that the channel water facilitates drug binding by increasing its entropy. Furthermore, the 2D IR spectral signatures obtained for both probes under different conditions collectively support a binding mechanism whereby amantadine-like drugs dock in the channel with their ammonium moiety pointing toward the histidine residues and interacting with a nearby water cluster, as predicted by molecular dynamics simulations. We believe these findings have important implications for designing new anti-influenza drugs.
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Affiliation(s)
- Ayanjeet Ghosh
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Jun Wang
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California 94143, USA
| | - Yurii S Moroz
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, USA
| | - Ivan V Korendovych
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, USA
| | - Martin Zanni
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - William F DeGrado
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California 94143, USA
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Robin M Hochstrasser
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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21
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Moran SD, Zhang TO, Zanni MT. An alternative structural isoform in amyloid-like aggregates formed from thermally denatured human γD-crystallin. Protein Sci 2014; 23:321-31. [PMID: 24415662 DOI: 10.1002/pro.2422] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/06/2014] [Accepted: 01/08/2014] [Indexed: 11/11/2022]
Abstract
The eye lens protein γD-crystallin contributes to cataract formation in the lens. In vitro experiments show that γD-crystallin has a high propensity to form amyloid fibers when denatured, and that denaturation by acid or UV-B photodamage results in its C-terminal domain forming the β-sheet core of amyloid fibers. Here, we show that thermal denaturation results in sheet-like aggregates that contain cross-linked oligomers of the protein, according to transmission electron microscopy and SDS-PAGE. We use two-dimensional infrared spectroscopy to show that these aggregates have an amyloid-like secondary structure with extended β-sheets, and use isotope dilution experiments to show that each protein contributes approximately one β-strand to each β-sheet in the aggregates. Using segmental (13) C labeling, we show that the organization of the protein's two domains in thermally induced aggregates results in a previously unobserved structure in which both the N-terminal and C-terminal domains contribute to β-sheets. We propose a model for the structural organization of the aggregates and attribute the recruitment of the N-terminal domain into the fiber structure to intermolecular cross linking.
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Affiliation(s)
- Sean D Moran
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706
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22
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Cai K, Su T, Lin S, Zheng R. Molecular mechanics force field-based general map for the solvation effect on amide I probe of peptide in different micro-environments. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 117:548-556. [PMID: 24036186 DOI: 10.1016/j.saa.2013.08.058] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 08/01/2013] [Accepted: 08/14/2013] [Indexed: 06/02/2023]
Abstract
A general electrostatic potential map based on molecular mechanics force field for modeling the amide I frequency is presented. This map is applied to N-methylacetamide (NMA) and designed to be transferable in different micro-environments. The electrostatic potentials from solvent and peptide side chain are projected on the amide unit of NMA to induce the frequency shift of amide I mode. It is shown that the predicted amide I frequency reproduces the experimental data satisfactorily, especially when NMA in polar solvents. The amide I frequency shift is largely determined by the solvents in aqueous solution while it is dominated by the local structure of peptide in other solvent environments. The map parameters are further applied on NMA-MeOH system and the obtained IR spectra show doublet peak profile with negligible deviation from the experimental data, suggesting the usefulness of this general map for providing information about vibrational parameters of amide motions of peptide in different environments.
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Affiliation(s)
- Kaicong Cai
- College of Chemistry and Chemical Engineering, Fujian Normal University, Fuzhou 350007, Fujian, PR China.
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23
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Abstract
This Perspective discusses applications of ultrafast transient 2D-IR spectroscopy methods to the study of inorganic excited states.
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Affiliation(s)
- N. T. Hunt
- Department of Physics
- University of Strathclyde
- Glasgow, UK
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24
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Zhao J, Shi J, Wang J. Amide-I characteristics of helical β-peptides by linear infrared measurement and computations. J Phys Chem B 2013; 118:94-106. [PMID: 24328259 DOI: 10.1021/jp4095936] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this work, we have examined the amide-I characteristics of three β-peptide oligomers in typical helical conformations (two in 14-helix and one in 12/10-helix), solvated in water, methanol, and chloroform, respectively. Local-mode frequencies and their distributions were computed using a molecular-mechanics force field based frequency map that was constructed on the basis of molecular dynamics simulations. The local-mode frequencies were found to be determined primarily by peptide backbone and side chain, rather by solvent, suggesting their local structural sensitivities. Intermode vibrational couplings computed using a transition dipole scheme were found to be very sensitive to peptide conformation, with their signs and magnitudes varying periodically along the peptide chain. Linear infrared absorption spectra of the three peptides, simulated using a frequency-frequency time-correlation function method, were found to be in fair agreement with experimental results. Normalized potential energy distribution analysis indicated that the amide-I mode can delocalize over a few amide units. However, the IR band structure appears to be more sophisticated in helical β-peptides than in helical α-peptides.
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Affiliation(s)
- Juan Zhao
- Beijing National Laboratory for Molecular Sciences, Molecular Reaction Dynamics Laboratory, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China
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25
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Zanetti-Polzi L, Aschi M, Amadei A, Daidone I. Simulation of the Amide I Infrared Spectrum in Photoinduced Peptide Folding/Unfolding Transitions. J Phys Chem B 2013; 117:12383-90. [DOI: 10.1021/jp406708p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Laura Zanetti-Polzi
- Dipartimento
di Scienze Fisiche e Chimiche, University of L’Aquila, via
Vetoio (Coppito 1), 67010 Coppito (AQ), Italy
- Center
S3, Institute of Nanoscience - CNR, Via Campi 213/A, 41125 Modena, Italy
| | - Massimiliano Aschi
- Dipartimento
di Scienze Fisiche e Chimiche, University of L’Aquila, via
Vetoio (Coppito 1), 67010 Coppito (AQ), Italy
| | - Andrea Amadei
- Dipartimento
di Scienze e Tecnologie Chimiche, University of Rome ”Tor Vergata”, via della Ricerca Scientifica 1, 00133 Rome, Italy
| | - Isabella Daidone
- Dipartimento
di Scienze Fisiche e Chimiche, University of L’Aquila, via
Vetoio (Coppito 1), 67010 Coppito (AQ), Italy
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26
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Lai Z, Preketes NK, Mukamel S, Wang J. Monitoring the folding of Trp-cage peptide by two-dimensional infrared (2DIR) spectroscopy. J Phys Chem B 2013; 117:4661-9. [PMID: 23448437 PMCID: PMC3893769 DOI: 10.1021/jp309122b] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Protein folding is one of the most fundamental problems in modern molecular biology. Uncovering the detailed folding mechanism requires methods that can monitor the structures at high temporal and spatial resolution. Two-dimensional infrared (2DIR) spectroscopy is a new tool for studying protein structures and dynamics with high time resolution. Using atomistic molecular dynamics simulations, we illustrate the folding process of Trp-cage along the dominant pathway on the free energy landscape by analyzing nonchiral and chiral coherent 2DIR spectra along the pathway. Isotope labeling is used to reveal residue-specific information. We show that the high resolution structural sensitivity of 2DIR can differentiate the ensemble evolution of protein and thus provides a microscopic picture of the folding process.
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Affiliation(s)
- Zaizhi Lai
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794
| | - Nicholas K. Preketes
- Department of Chemistry, University of California, Irvine, Irvine, CA, 92697-2025
| | - Shaul Mukamel
- Department of Chemistry, University of California, Irvine, Irvine, CA, 92697-2025
| | - Jin Wang
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794
- Department of Physics and Applied Mathematics & Statistics, State University of New York at Stony Brook, Stony Brook, NY 11794
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130021, People’s Republic of China
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27
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Szymański W, Beierle JM, Kistemaker HAV, Velema WA, Feringa BL. Reversible Photocontrol of Biological Systems by the Incorporation of Molecular Photoswitches. Chem Rev 2013; 113:6114-78. [DOI: 10.1021/cr300179f] [Citation(s) in RCA: 847] [Impact Index Per Article: 77.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Wiktor Szymański
- Stratingh Institute
for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The
Netherlands
| | - John M. Beierle
- Stratingh Institute
for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The
Netherlands
| | - Hans A. V. Kistemaker
- Stratingh Institute
for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The
Netherlands
| | - Willem A. Velema
- Stratingh Institute
for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The
Netherlands
| | - Ben L. Feringa
- Stratingh Institute
for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The
Netherlands
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28
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Folding of a heterogeneous β-hairpin peptide from temperature-jump 2D IR spectroscopy. Proc Natl Acad Sci U S A 2013; 110:2828-33. [PMID: 23382249 DOI: 10.1073/pnas.1211968110] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We provide a time- and structure-resolved characterization of the folding of the heterogeneous β-hairpin peptide Tryptophan Zipper 2 (Trpzip2) using 2D IR spectroscopy. The amide I' vibrations of three Trpzip2 isotopologues are used as a local probe of the midstrand contacts, β-turn, and overall β-sheet content. Our experiments distinguish between a folded state with a type I' β-turn and a misfolded state with a bulged turn, providing evidence for distinct conformations of the peptide backbone. Transient 2D IR spectroscopy at 45 °C following a laser temperature jump tracks the nanosecond and microsecond kinetics of unfolding and the exchange between conformers. Hydrogen bonds to the peptide backbone are loosened rapidly compared with the 5-ns temperature jump. Subsequently, all relaxation kinetics are characterized by an observed 1.2 ± 0.2-μs exponential. Our time-dependent 2D IR spectra are explained in terms of folding of either native or nonnative contacts from a common compact disordered state. Conversion from the disordered state to the folded state is consistent with a zip-out folding mechanism.
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29
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Remorino A, Hochstrasser RM. Three-dimensional structures by two-dimensional vibrational spectroscopy. Acc Chem Res 2012; 45:1896-905. [PMID: 22458539 PMCID: PMC3392492 DOI: 10.1021/ar3000025] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The development of experiments that can generate molecular movies of changing chemical structures is a major challenge for physical chemistry. But to realize this dream, we not only need to significantly improve existing approaches but also must invent new technologies. Most of the known protein structures have been determined by X-ray diffraction and to lesser extent by NMR. Though powerful, X-ray diffraction presents limitations for acquiring time-dependent structures. In the case of NMR, ultrafast equilibrium dynamics might be inferred from line shapes, but the structures of conformations interconverting on such time scales are not realizable. This Account highlights two-dimensional infrared spectroscopy (2D IR), in particular the 2D vibrational echo, as an approach to time-resolved structure determination. We outline the use of the 2D IR method to completely determine the structure of a protein of the integrin family in a time window of few picoseconds. As a transmembrane protein, this class of structures has proved particularly challenging for the established structural methodologies of X-ray crystallography and NMR. We describe the challenges facing multidimensional spectroscopy and compare it with some other methods of structural biology. Then we succinctly discuss the basic principles of 2D IR methods as they relate to time domain and frequency domain experimental and theoretical properties required for protein structure determination. By means of the example of the transmembrane protein, we describe the essential aspects of combined carbon-13-oxygen-18 isotope labels to create vibrational resonance pairs that allow the determination of protein and peptide structures in motion. Finally, we propose a three-dimensional structure of the αIIb transmembrane homodimer that includes optimum locations of all side chains and backbone atoms of the protein.
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Affiliation(s)
- Amanda Remorino
- Department of Chemistry, University of Pennsylvania, Philadelphia Pa 19104
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30
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Bloem R, Koziol K, Waldauer SA, Buchli B, Walser R, Samatanga B, Jelesarov I, Hamm P. Ligand Binding Studied by 2D IR Spectroscopy Using the Azidohomoalanine Label. J Phys Chem B 2012; 116:13705-12. [DOI: 10.1021/jp3095209] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Robbert Bloem
- Institute of Physical Chemistry, University of Zurich, Zurich 8057, Switzerland
| | - Klemens Koziol
- Institute of Physical Chemistry, University of Zurich, Zurich 8057, Switzerland
| | - Steven A. Waldauer
- Institute of Physical Chemistry, University of Zurich, Zurich 8057, Switzerland
| | - Brigitte Buchli
- Institute of Physical Chemistry, University of Zurich, Zurich 8057, Switzerland
| | - Reto Walser
- Institute of Physical Chemistry, University of Zurich, Zurich 8057, Switzerland
| | - Brighton Samatanga
- Department of Biochemistry, University of Zurich, Zurich 8057, Switzerland
- Institute of Molecular Biology
and Biophysics, ETH Zurich, Zurich 8093,
Switzerland
| | - Ilian Jelesarov
- Department of Biochemistry, University of Zurich, Zurich 8057, Switzerland
| | - Peter Hamm
- Institute of Physical Chemistry, University of Zurich, Zurich 8057, Switzerland
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31
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Anna JM, Baiz CR, Ross MR, McCanne R, Kubarych KJ. Ultrafast equilibrium and non-equilibrium chemical reaction dynamics probed with multidimensional infrared spectroscopy. INT REV PHYS CHEM 2012. [DOI: 10.1080/0144235x.2012.716610] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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32
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Serrano AL, Waegele MM, Gai F. Spectroscopic studies of protein folding: linear and nonlinear methods. Protein Sci 2012; 21:157-70. [PMID: 22109973 PMCID: PMC3324760 DOI: 10.1002/pro.2006] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 11/15/2011] [Indexed: 01/08/2023]
Abstract
Although protein folding is a simple outcome of the underlying thermodynamics, arriving at a quantitative and predictive understanding of how proteins fold nevertheless poses huge challenges. Therefore, both advanced experimental and computational methods are continuously being developed and refined to probe and reveal the atomistic details of protein folding dynamics and mechanisms. Herein, we provide a concise review of recent developments in spectroscopic studies of protein folding, with a focus on new triggering and probing methods. In particular, we describe several laser-based techniques for triggering protein folding/unfolding on the picosecond and/or nanosecond timescales and various linear and nonlinear spectroscopic techniques for interrogating protein conformations, conformational transitions, and dynamics.
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Affiliation(s)
- Arnaldo L Serrano
- Department of Chemistry, University of PennsylvaniaPhiladelphia, Pennsylvania 19104
| | - Matthias M Waegele
- Department of Chemistry, University of PennsylvaniaPhiladelphia, Pennsylvania 19104
| | - Feng Gai
- Department of Chemistry, University of PennsylvaniaPhiladelphia, Pennsylvania 19104
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33
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Thielges MC, Axup JY, Wong D, Lee HS, Chung JK, Schultz PG, Fayer MD. Two-dimensional IR spectroscopy of protein dynamics using two vibrational labels: a site-specific genetically encoded unnatural amino acid and an active site ligand. J Phys Chem B 2011; 115:11294-304. [PMID: 21823631 PMCID: PMC3261801 DOI: 10.1021/jp206986v] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Protein dynamics and interactions in myoglobin (Mb) were characterized via two vibrational dynamics labels (VDLs): a genetically incorporated site-specific azide (Az) bearing unnatural amino acid (AzPhe43) and an active site CO ligand. The Az-labeled protein was studied using ultrafast two-dimensional infrared (2D IR) vibrational echo spectroscopy. CO bound at the active site of the heme serves as a second VDL located nearby. Therefore, it was possible to use Fourier transform infrared (FT-IR) and 2D IR spectroscopic experiments on the Az in unligated Mb and in Mb bound to CO (MbAzCO) and on the CO in MbCO and MbAzCO to investigate the environment and motions of different states of one protein from the perspective of two spectrally resolved VDLs. A very broad bandwidth 2D IR spectrum, encompassing both the Az and CO spectral regions, found no evidence of direct coupling between the two VDLs. In MbAzCO, both VDLs reported similar time scale motions: very fast homogeneous dynamics, fast, ∼1 ps dynamics, and dynamics on a much slower time scale. Therefore, each VDL reports independently on the protein dynamics and interactions, and the measured dynamics are reflective of the protein motions rather than intrinsic to the chemical nature of the VDL. The AzPhe VDL also permitted study of oxidized Mb dynamics, which could not be accessed previously with 2D IR spectroscopy. The experiments demonstrate that the combined application of 2D IR spectroscopy and site-specific incorporation of VDLs can provide information on dynamics, structure, and interactions at virtually any site throughout any protein.
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Affiliation(s)
- Megan C. Thielges
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Jun Y. Axup
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Daryl Wong
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Hyun Soo Lee
- Department of Chemistry, Sogang University, Seoul 121-742, Korea
| | - Jean K. Chung
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Peter G. Schultz
- Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Michael D. Fayer
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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34
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Fatás P, Longo E, Rastrelli F, Crisma M, Toniolo C, Jiménez AI, Cativiela C, Moretto A. Bis(azobenzene)-based photoswitchable, prochiral, Cα-tetrasubstituted α-amino acids for nanomaterials applications. Chemistry 2011; 17:12606-11. [PMID: 21956889 DOI: 10.1002/chem.201102609] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Indexed: 11/06/2022]
Affiliation(s)
- Paola Fatás
- Department of Organic Chemistry, ISQCH, University of Zaragoza-CSIC, Zaragoza, Spain
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35
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Middleton CT, Buchanan LE, Dunkelberger EB, Zanni MT. Utilizing Lifetimes to Suppress Random Coil Features in 2D IR Spectra of Peptides. J Phys Chem Lett 2011; 2:2357-2361. [PMID: 21966585 PMCID: PMC3182477 DOI: 10.1021/jz201024m] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We report that the waiting time delay in 2D IR pulse sequences can be used to suppress signals from structurally disordered regions of amyloid fibrils. At a waiting time delay of 1.0 ps, the random coil vibrational modes of amylin fibrils are no longer detectable, leaving only the sharp excitonic vibrational features of the fibril β-sheets. Isotope labeling with (13)C(18)O reveals that structurally disordered residues decay faster than residues protected from solvent. Since structural disorder is usually accompanied by hydration, we conclude that the shorter lifetimes of random-coil residues is due to solvent exposure. These results indicate that 2D IR pulse sequences can utilize the waiting time to better resolve solvent-protected regions of peptides and that local mode lifetimes should be included in simulations of 2D IR spectra.
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36
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Abstract
The nucleation event in α-helix formation is a fundamental process in protein folding. However, determining how quickly it takes place based on measurements of the relaxation dynamics of helical peptides is difficult because such relaxations invariably contain contributions from various structural transitions such as from helical to nonhelical states and helical to partial-helical conformations. Herein, we measure the temperature-jump (T-jump) relaxation kinetics of three model peptides that fold into a single-turn α-helix, using time-resolved infrared spectroscopy, aiming to provide a direct assessment of the helix nucleation rate. The α-helical structure of these peptides is stabilized by a covalent cross-linker formed between the side chains of two residues at the i and i + 4 positions. If we assume that this cross-linker mimics the structural constraint arising from a strong side chain-side chain interaction (e.g., a salt bridge) in proteins, these peptides would represent good models for studying the nucleation process of an α-helix in a protein environment. Indeed, we find that the T-jump induced relaxation rate of these peptides is approximately (0.6 μs)(-1) at room temperature, which is slower than that of commonly studied alanine-based helical peptides but faster than that of a naturally occurring α-helix whose folded state is stabilized by a series of side chain-side chain interactions. Taken together, our results put an upper limit of about 1 μs for the helix nucleation time at 20 °C and suggest that the subsequent propagation steps occur with a time constant of about 240 ns.
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Affiliation(s)
| | | | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
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37
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Baiz CR, Kubarych KJ, Geva E, Sibert EL. Local-mode approach to modeling multidimensional infrared spectra of metal carbonyls. J Phys Chem A 2011; 115:5354-63. [PMID: 21545166 DOI: 10.1021/jp201641h] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We present a general approach for modeling multidimensional infrared spectra based on a combination of phenomenological fitting and ab initio electronic structure calculations. The vibrational Hamiltonian is written in terms of bilinearly coupled Morse oscillators that represent local carbonyl stretches. This should be contrasted with the previous approach, where the anharmonic Hamiltonian was given in terms of normal-mode coordinates ( Baiz et al. J. Phys. Chem. A 2009 , 113 , 9617 ). The bilinearly coupled Morse oscillator Hamiltonian is parametrized such that the frequencies and couplings are consistent with experiment, and the anharmonicities are computed by density functional theory. The advantages of the local-mode versus normal-mode approaches are discussed, as well as the ability of different density functionals to provide accurate estimates of the model parameters. The applicability and usefulness of the new approach are demonstrated in the context of the recently measured multidimensional infrared spectra of dimanganese decacarbonyl. The shifts in local site frequencies, couplings, and anharmonicities due to hydrogen bonding to the individual carbonyls are explored. It is found that, even though the effect of hydrogen bonding is nonlocal, it is additive.
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Affiliation(s)
- Carlos R Baiz
- Department of Chemistry, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, USA
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38
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Tidal surge in the M2 proton channel, sensed by 2D IR spectroscopy. Proc Natl Acad Sci U S A 2011; 108:6115-20. [PMID: 21444789 DOI: 10.1073/pnas.1103027108] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The M2 proton channel from influenza A virus transmits protons across membranes via a narrow aqueous pore lined by water and a proton sensor, His37. Near the center of the membrane, a water cluster is stabilized by the carbonyl of Gly34 and His37, the properties of which are modulated by protonation of His37. At low pH (5-6), where M2 conducts protons, this region undergoes exchange processes on the microsecond to second timescale. Here, we use 2D IR to examine the instantaneous conformational distribution and hydration of G34, and the evolution of the ensemble on the femtosecond to picosecond timescale. The channel water is strongly pH dependent as gauged by 2D IR which allows recording of the vibrational frequency autocorrelation function of a (13)C = (18)O Gly34 probe. At pH 8, where entry and exit of protons within the channel are very slow, the carbonyl groups appear to adopt a single conformation/environment. The high-pH conformer does not exhibit spectral dynamics near the Gly34, and water in the channel must form a relatively rigid ice-like structure. By contrast, two vibrational forms of G34 are seen at pH 6.2, neither of which is identical to the high-pH form. In at least one of these low-pH forms, the probe is immersed in a very mobile, bulk-like aqueous environment having a correlation time ca. 1.3 ps at pH 6.2. Thus, protonation of His37 at low pH causes liquid-like water molecules to flow into the neighborhood of the Gly34.
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39
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Thielges MC, Chung JK, Fayer MD. Protein dynamics in cytochrome P450 molecular recognition and substrate specificity using 2D IR vibrational echo spectroscopy. J Am Chem Soc 2011; 133:3995-4004. [PMID: 21348488 PMCID: PMC3063108 DOI: 10.1021/ja109168h] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cytochrome (cyt) P450s hydroxylate a variety of substrates that can differ widely in their chemical structure. The importance of these enzymes in drug metabolism and other biological processes has motivated the study of the factors that enable their activity on diverse classes of molecules. Protein dynamics have been implicated in cyt P450 substrate specificity. Here, 2D IR vibrational echo spectroscopy is employed to measure the dynamics of cyt P450(cam) from Pseudomonas putida on fast time scales using CO bound at the active site as a vibrational probe. The substrate-free enzyme and the enzyme bound to both its natural substrate, camphor, and a series of related substrates are investigated to explicate the role of dynamics in molecular recognition in cyt P450(cam) and to delineate how the motions may contribute to hydroxylation specificity. In substrate-free cyt P450(cam), three conformational states are populated, and the structural fluctuations within a conformational state are relatively slow. Substrate binding selectively stabilizes one conformational state, and the dynamics become faster. Correlations in the observed dynamics with the specificity of hydroxylation of the substrates, the binding affinity, and the substrates' molecular volume suggest that motions on the hundreds of picosecond time scale contribute to the variation in activity of cyt P450(cam) toward different substrates.
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Affiliation(s)
| | - Jean K. Chung
- Department of Chemistry, Stanford University, Stanford, CA 94305
| | - Michael D. Fayer
- Department of Chemistry, Stanford University, Stanford, CA 94305
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Meng K, Wang J. Anharmonic overtone and combination states of glycine and two model peptides examined by vibrational self-consistent field theory. Phys Chem Chem Phys 2011; 13:2001-13. [DOI: 10.1039/c0cp01177k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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