1
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Thomassen AB, Jansen TLC, Weidner T. The secondary structure of diatom silaffin peptide R5 determined by two-dimensional infrared spectroscopy. Phys Chem Chem Phys 2024; 26:18538-18546. [PMID: 38888161 DOI: 10.1039/d4cp00970c] [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: 06/20/2024]
Abstract
Diatoms, unicellular marine organisms, harness short peptide repeats of the protein silaffin to transform silicic acid into biosilica nanoparticles. This process has been a white whale for material scientists due to its potential in biomimetic applications, ranging from medical to microelectronic fields. Replicating diatom biosilicification will depend on a thorough understanding of the silaffin peptide structure during the reaction, yet existing models in the literature offer conflicting views on peptide folding during silicification. In our study, we employed two-dimensional infrared spectroscopy (2DIR) within the amide I region to determine the secondary structure of the silaffin repeat unit 5 (R5), both pre- and post-interaction with silica. The 2DIR experiments are complemented by molecular dynamics (MD) simulations of pure R5 reacting with silicate. Subsequently, theoretical 2DIR spectra calculated from these MD trajectories allowed us to compare calculated spectra with experimental data, and to determine the diverse structural poses of R5. Our findings indicate that unbound R5 predominantly forms β-strand structures alongside various atypical secondary structures. Post-silicification, there's a noticeable shift: a decrease in β-strands coupled with an increase in turn-type and bend-type configurations. We theorize that this structural transformation stems from silicate embedding within R5's hydrogen-bond network, prompting the peptide backbone to contract and adapt around the biosilica precursors.
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Affiliation(s)
- Asger Berg Thomassen
- Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus C 8000, Denmark.
| | - Thomas L C Jansen
- Zernike Institute for Advanced Materials, University of Groningen, Groningen 9747 AG, The Netherlands.
| | - Tobias Weidner
- Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus C 8000, Denmark.
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2
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Konstantinovsky D, Santiago T, Tremblay M, Simpson GJ, Hammes-Schiffer S, Yan ECY. Theoretical basis for interpreting heterodyne chirality-selective sum frequency generation spectra of water. J Chem Phys 2024; 160:055102. [PMID: 38341693 DOI: 10.1063/5.0181718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 01/08/2024] [Indexed: 02/13/2024] Open
Abstract
Chirality-selective vibrational sum frequency generation (chiral SFG) spectroscopy has emerged as a powerful technique for the study of biomolecular hydration water due to its sensitivity to the induced chirality of the first hydration shell. Thus far, water O-H vibrational bands in phase-resolved heterodyne chiral SFG spectra have been fit using one Lorentzian function per vibrational band, and the resulting fit has been used to infer the underlying frequency distribution. Here, we show that this approach may not correctly reveal the structure and dynamics of hydration water. Our analysis illustrates that the chiral SFG responses of symmetric and asymmetric O-H stretch modes of water have opposite phase and equal magnitude and are separated in energy by intramolecular vibrational coupling and a heterogeneous environment. The sum of the symmetric and asymmetric responses implies that an O-H stretch in a heterodyne chiral SFG spectrum should appear as two peaks with opposite phase and equal amplitude. Using pairs of Lorentzian functions to fit water O-H stretch vibrational bands, we improve spectral fitting of previously acquired experimental spectra of model β-sheet proteins and reduce the number of free parameters. The fitting allows us to estimate the vibrational frequency distribution and thus reveals the molecular interactions of water in hydration shells of biomolecules directly from chiral SFG spectra.
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Affiliation(s)
- Daniel Konstantinovsky
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Ty Santiago
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Matthew Tremblay
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Garth J Simpson
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Elsa C Y Yan
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
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3
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Brüggemann J, Wolter M, Jacob CR. Quantum-chemical calculation of two-dimensional infrared spectra using localized-mode VSCF/VCI. J Chem Phys 2022; 157:244107. [PMID: 36586972 DOI: 10.1063/5.0135273] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Computational protocols for the simulation of two-dimensional infrared (2D IR) spectroscopy usually rely on vibrational exciton models which require an empirical parameterization. Here, we present an efficient quantum-chemical protocol for predicting static 2D IR spectra that does not require any empirical parameters. For the calculation of anharmonic vibrational energy levels and transition dipole moments, we employ the localized-mode vibrational self-consistent field (L-VSCF)/vibrational configuration interaction (L-VCI) approach previously established for (linear) anharmonic theoretical vibrational spectroscopy [P. T. Panek and C. R. Jacob, ChemPhysChem 15, 3365-3377 (2014)]. We demonstrate that with an efficient expansion of the potential energy surface using anharmonic one-mode potentials and harmonic two-mode potentials, 2D IR spectra of metal carbonyl complexes and dipeptides can be predicted reliably. We further show how the close connection between L-VCI and vibrational exciton models can be exploited to extract the parameters of such models from those calculations. This provides a novel route to the fully quantum-chemical parameterization of vibrational exciton models for predicting 2D IR spectra.
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Affiliation(s)
- Julia Brüggemann
- Institute of Physical and Theoretical Chemistry, Technische Universität Braunschweig, Gaußstraße 17, 38106 Braunschweig, Germany
| | - Mario Wolter
- Institute of Physical and Theoretical Chemistry, Technische Universität Braunschweig, Gaußstraße 17, 38106 Braunschweig, Germany
| | - Christoph R Jacob
- Institute of Physical and Theoretical Chemistry, Technische Universität Braunschweig, Gaußstraße 17, 38106 Braunschweig, Germany
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4
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Liu G, Fan Y, Tao Y, Wang S, Wang M, Li L. Interactions of potato-derived and human recombinant 5-lipoxygenase with sec-O-glucosylhamaudol by multi-spectroscopy and molecular docking. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 274:121100. [PMID: 35272121 DOI: 10.1016/j.saa.2022.121100] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 02/23/2022] [Accepted: 02/26/2022] [Indexed: 06/14/2023]
Abstract
5-lipoxygenase (5-LOX) was a key enzyme involved in many inflammatory diseases. Sec-O-glucosylhamaudol (SOG) was a chromone found in Saposhnikovia divaricata (Turcz.) Schischk (S. divaricate). The potato-derived 5-LOX (p-5-LOX) and human recombinant 5-LOX (h-5-LOX) were selected as model protein due to their simple usability and high stability in this study. Thus, the binding interactions of p-5-LOX and h-5-LOX with SOG were investigated by multi-spectroscopy and molecular docking. As a result, the fluorescence intensities of the two 5-LOX were quenched statically by SOG. However, the binding ability of SOG to h-5-LOX was higher than that of p-5-LOX at the same temperature. The results of multi-spectroscopy revealed that the conformation and micro-environment of the two 5-LOX proteins were changed after binding with SOG. Fluorescence assay and molecular docking indicated that hydrogen bond and electrostatic gravitation were the main forces between the two 5-LOX and SOG. Our results here suggested that SOG may exert anti-inflammatory effect by inhibiting 5-LOX activity.
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Affiliation(s)
- Guiming Liu
- The College of Chemistry, Changchun Normal University, Changchun 130032, China
| | - Yangyang Fan
- The College of Chemistry, Changchun Normal University, Changchun 130032, China
| | - Yanzhou Tao
- The College of Chemistry, Changchun Normal University, Changchun 130032, China
| | - Suqing Wang
- The College of Chemistry, Changchun Normal University, Changchun 130032, China
| | - Meizi Wang
- The College of Chemistry, Changchun Normal University, Changchun 130032, China
| | - Li Li
- The College of Chemistry, Changchun Normal University, Changchun 130032, China.
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5
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van Adrichem KE, Jansen TLC. AIM: A Mapping Program for Infrared Spectroscopy of Proteins. J Chem Theory Comput 2022; 18:3089-3098. [PMID: 35387451 PMCID: PMC9097285 DOI: 10.1021/acs.jctc.2c00113] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
Here, we present
a new analysis program, AIM, that allows extracting
the vibrational amide-I Hamiltonian using molecular dynamics trajectories
for protein infrared spectroscopy modeling. The constructed Hamiltonians
can be used as input for spectral calculations allowing the calculation
of infrared absorption spectra, vibrational circular dichroism, and
two-dimensional infrared spectra. These spectroscopies allow the study
of the structure and dynamics of proteins. We will explain the essence
of how AIM works and give examples of the information and spectra
that can be obtained with the program using the Trypsin Inhibitor
as an example. AIM is freely available from GitHub, and the package
contains a demonstration allowing easy introduction to the use of
the program.
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Affiliation(s)
- Kim E van Adrichem
- Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Thomas L C Jansen
- Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
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6
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Heussman D, Kittell J, von Hippel PH, Marcus AH. Temperature-dependent local conformations and conformational distributions of cyanine dimer labeled single-stranded-double-stranded DNA junctions by 2D fluorescence spectroscopy. J Chem Phys 2022; 156:045101. [PMID: 35105081 PMCID: PMC9448411 DOI: 10.1063/5.0076261] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
DNA replication and the related processes of genome expression require binding, assembly, and function of protein complexes at and near single-stranded (ss)-double-stranded (ds) DNA junctions. These central protein-DNA interactions are likely influenced by thermally induced conformational fluctuations of the DNA scaffold across an unknown distribution of functionally relevant states to provide regulatory proteins access to properly conformed DNA binding sites. Thus, characterizing the nature of conformational fluctuations and the associated structural disorder at ss-dsDNA junctions is critical for understanding the molecular mechanisms of these central biological processes. Here, we describe spectroscopic studies of model ss-dsDNA fork constructs that contain dimers of "internally labeled" cyanine (iCy3) chromophore probes that have been rigidly inserted within the sugar-phosphate backbones of the DNA strands. Our combined analyses of absorbance, circular dichroism, and two-dimensional fluorescence spectroscopy permit us to characterize the local conformational parameters and conformational distributions. We find that the DNA sugar-phosphate backbones undergo abrupt successive changes in their local conformations-initially from a right-handed and ordered DNA state to a disordered splayed-open structure and then to a disordered left-handed conformation-as the dimer probes are moved across the ss-dsDNA junction. Our results suggest that the sugar-phosphate backbones at and near ss-dsDNA junctions adopt specific position-dependent local conformations and exhibit varying extents of conformational disorder that deviate widely from the Watson-Crick structure. We suggest that some of these conformations can function as secondary-structure motifs for interaction with protein complexes that bind to and assemble at these sites.
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Affiliation(s)
| | - Justin Kittell
- Center for Optical, Molecular and Quantum Science, Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403, USA
| | - Peter H. von Hippel
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA
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7
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Edun DN, Cracchiolo OM, Serrano AL. A theoretical analysis of coherent cross-peaks in polarization selective 2DIR for detection of cross-α fibrils. J Chem Phys 2022; 156:035102. [DOI: 10.1063/5.0070553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Dean N. Edun
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Olivia M. Cracchiolo
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Arnaldo L. Serrano
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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8
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Pinto SMV, Tasinato N, Barone V, Zanetti-Polzi L, Daidone I. A computational insight into the relationship between side chain IR line shapes and local environment in fibril-like structures. J Chem Phys 2021; 154:084105. [PMID: 33639764 DOI: 10.1063/5.0038913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Infrared spectroscopy is a widely used technique to characterize protein structures and protein mediated processes. While the amide I band provides information on proteins' secondary structure, amino acid side chains are used as infrared probes for the investigation of protein reactions and local properties. In this paper, we use a hybrid quantum mechanical/classical molecular dynamical approach based on the perturbed matrix method to compute the infrared band due to the C=O stretching mode of amide-containing side chains. We calculate, at first, the infrared band of zwitterionic glutamine in water and obtain results in very good agreement with the experimental data. Then, we compute the signal arising from glutamine side chains in a microcrystal of the yeast prion Sup35-derived peptide, GNNQQNY, with a fibrillar structure. The infrared bands obtained by selective isotopic labeling of the two glutamine residues, Q4 and Q5, of each peptide were experimentally used to investigate the local hydration in the fibrillar microcrystal. The experimental spectra of the two glutamine residues, which experience different hydration environments, feature different spectral signals that are well reproduced by the corresponding calculated spectra. In addition, the analysis of the simulated spectra clarifies the molecular origin of the experimentally observed spectroscopic differences that arise from the different local electric field experienced by the two glutamine residues, which is, in turn, determined by a different hydrogen bonding pattern.
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Affiliation(s)
- Sandra M V Pinto
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
| | - Nicola Tasinato
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
| | - Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
| | | | - Isabella Daidone
- Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio, I-67100 L'Aquila, Italy
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9
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Xie Z, He M, Zhai Y, Xin F, Yu S, Yu S, Xiao H, Song Y. Inhibitory kinetics and mechanism of oleanolic acid on α-glucosidase. JOURNAL OF FOOD MEASUREMENT AND CHARACTERIZATION 2021. [DOI: 10.1007/s11694-021-00920-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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10
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Edun DN, Flanagan MR, Serrano AL. Does liquid-liquid phase separation drive peptide folding? Chem Sci 2020; 12:2474-2479. [PMID: 34164013 PMCID: PMC8179267 DOI: 10.1039/d0sc04993j] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Proline–arginine (PR) dipeptide repeats have been shown to undergo liquid–liquid phase separation and are an example of a growing number of intrinsically disordered proteins that can assemble into membraneless organelles. These structures have been posited as nucleation sites for pathogenic protein aggregation. As such, a better understanding of the effects that the increased local concentration and volumetric crowding within droplets have on peptide secondary structure is necessary. Herein we use Fourier transform infrared (FTIR) and two-dimensional infrared (2DIR) spectroscopy to show that formation of droplets by PR20 accompanies changes in the amide-I spectra consistent with folding into poly-proline helical structures. Two-dimensional infrared spectroscopy reveals folding of an intrinsically disordered peptide when sequestered into a model “membrane-less” organelle.![]()
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Affiliation(s)
- Dean N Edun
- Department of Chemistry and Biochemistry, University of Notre Dame Notre Dame Indiana 46556 USA
| | - Meredith R Flanagan
- Department of Chemistry and Biochemistry, University of Notre Dame Notre Dame Indiana 46556 USA
| | - Arnaldo L Serrano
- Department of Chemistry and Biochemistry, University of Notre Dame Notre Dame Indiana 46556 USA
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11
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Gobeze HB, Ma J, Leonik FM, Kuroda DG. Bottom-Up Approach to Assess the Molecular Structure of Aqueous Poly( N-Isopropylacrylamide) at Room Temperature via Infrared Spectroscopy. J Phys Chem B 2020; 124:11699-11710. [PMID: 33306373 PMCID: PMC7872429 DOI: 10.1021/acs.jpcb.0c08424] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The structure of poly(N-isopropylacrylamide) (PNIPAM) in solution is still an unresolved topic. Here, the PNIPAM structure in water was investigated using a bottom-up approach, involving the monomer, dimer, and trimer, and a combination of infrared (IR) spectroscopies as well as molecular dynamics simulations. The experiments show that the monomer and oligomers exhibit a broad and asymmetric amide I band with two underlying transitions, while PNIPAM presents the same major transitions and a minor one. Analysis of the 2D IR spectra and theoretical modeling of the amide I band indicates that the two transitions of the monomer do not have the same molecular origin as the oligomers and the polymer. In the monomer, the two bands originate from the ultrafast rotation of its ethyl group, which leads to different solvation structures for the various rotational conformers. In the case of the oligomers, the asymmetry and splitting of the amide I band is caused by the vibrational coupling among adjacent amide side chains. Moreover, it is deduced from the simulations that the oligomers have three distinct backbone conformations for neighboring amides. In particular, two of the backbone conformations have a closed and compact structure, while in the third, the backbone is open and elongated. The bottom-up approach allowed us to infer that such backbone conformations exist in PNIPAM as well. Consequently, the two major amide I transitions of the polymer are also assigned to split amide I transitions resulting from the vibrationally coupled nearest-neighboring amides. In contrast, the additional minor transition observed in PNIPAM is assigned to unsolvated amide units of the polymer. The proposed molecular model successfully describes that PNIPAM amide I band changes with temperature in terms of its molecular structure. This new model strongly suggests that PNIPAM does not have a completely random backbone structure, but has distinct backbone conformers between neighboring amides.
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Affiliation(s)
- Habtom B Gobeze
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Jianbo Ma
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Fedra M Leonik
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Daniel G Kuroda
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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12
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Zhao J, Huang L, Sun C, Zhao D, Tang H. Studies on the structure-activity relationship and interaction mechanism of flavonoids and xanthine oxidase through enzyme kinetics, spectroscopy methods and molecular simulations. Food Chem 2020; 323:126807. [PMID: 32330646 DOI: 10.1016/j.foodchem.2020.126807] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 03/25/2020] [Accepted: 04/13/2020] [Indexed: 12/14/2022]
Abstract
In this study, some flavonoids were screened as potent xanthine oxidase (XO) inhibitors in vitro. Flavonoid 9 was demonstrated to exhibit the inhibitory activity through a ping-pong mechanism. Further structure-activity relationship revealed that different structural elements had greatly influenced the inhibition effect on XO and underlined the requirement of hydroxyl groups at C5 and C4' of flavonoid type I. Moreover, some bioactive flavonoids could efficiently quench the intrinsic fluorescence of XO by either static or static-dynamic mixed mechanism. The synchronous fluorescence, ANS-binding fluorescence, Fourier transform infrared spectra and circular dichroism suggested that active flavonoids could bind to the active center of XO, prevent the entrance of substrate, and induce the rearrangement and conformation change of its secondary structures, ultimately resulting in the significant inhibition effect. Additionally, molecular docking further confirmed these conclusions and highlighted the great importance of hydrophobic interactions and hydrogen bonds for the formation of stable complex conformation.
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Affiliation(s)
- Jie Zhao
- College of Biological and Chemical Engineering, Anhui Polytechnic University, Wuhu 241000, PR China
| | - Lin Huang
- Blood Purification Center, Affiliated Yijishan Hospital of Wannan Medical College, Wuhu 241001, PR China
| | - Chunyong Sun
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, PR China
| | - Dongsheng Zhao
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, PR China.
| | - Hongjin Tang
- College of Biological and Chemical Engineering, Anhui Polytechnic University, Wuhu 241000, PR China.
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13
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Vieira Pinto SM, Tasinato N, Barone V, Amadei A, Zanetti-Polzi L, Daidone I. Modeling amino-acid side chain infrared spectra: the case of carboxylic residues. Phys Chem Chem Phys 2020; 22:3008-3016. [DOI: 10.1039/c9cp04774c] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Infrared (IR) spectroscopy is commonly utilized for the investigation of protein structures and protein-mediated processes.
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Affiliation(s)
- Sandra Mónica Vieira Pinto
- Scuola Normale Superiore
- I-56126 Pisa
- Italy
- Department of Physical and Chemical Sciences
- University of L'Aquila
| | | | | | - Andrea Amadei
- Department of Chemical and Technological Sciences
- University of Rome “Tor Vergata
- I-00185 Rome
- Italy
| | - Laura Zanetti-Polzi
- Department of Physical and Chemical Sciences
- University of L'Aquila
- I-67010 L'Aquila
- Italy
- CNR Institute of Nanoscience
| | - Isabella Daidone
- Department of Physical and Chemical Sciences
- University of L'Aquila
- I-67010 L'Aquila
- Italy
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14
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Tang H, Ma F, Zhao D. Integrated multi-spectroscopic and molecular modelling techniques to probe the interaction mechanism between salvianolic acid A and α‑glucosidase. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2019; 218:51-61. [PMID: 30954797 DOI: 10.1016/j.saa.2019.03.109] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 03/21/2019] [Accepted: 03/28/2019] [Indexed: 06/09/2023]
Abstract
α-Glucosidase (AG) is an important drug target for the treatment of type 2 diabetes mellitus in humans due to the potential effect of down regulating glucose absorption in patients. In our previous study, salvianolic acid A (SAA) was found to exhibit potent AG inhibitory activity, whereas the interaction mechanism was still ambiguous. Herein, the interaction mechanism of SAA and AG was investigated by multi-spectroscopic methods along with molecular docking. As a result, it was found that SAA reversibly inhibited AG in a competitive manner with IC50 of 16.44 ± 0.18 μM, and the inhibition belonged to a multi-phase kinetics process with a first-order reaction. The intrinsic fluorescence of AG could be strongly quenched by SAA through a static quenching mechanism. The negative Gibbs free energy change and positive values of enthalpy and entropy change revealed that the binding of SAA to AG was spontaneous and dominated mainly by hydrophobic interactions, and only a single binding site was determined for them. Analysis of synchronous fluorescence, ANS-binding fluorescence, circular dichroism and Fourier transform infrared spectra suggested that the binding of SAA to AG induced rearrangement and conformational changes of the enzyme. Besides, further molecular modelling validated that SAA could bind to the active domain and prevent the entrance of substrate, resulting in the inhibition of AG activity. These findings provide new insights into understanding the interaction mechanism of SAA on AG.
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Affiliation(s)
- Hongjin Tang
- College of Biological and Chemical Engineering, Anhui Polytechnic University, Wuhu 241000, PR China.
| | - Fei Ma
- Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan 250011, PR China
| | - Dongsheng Zhao
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, PR China
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15
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Effect of Salvia miltiorrhiza on acetylcholinesterase: Enzyme kinetics and interaction mechanism merging with molecular docking analysis. Int J Biol Macromol 2019; 135:303-313. [PMID: 31128195 DOI: 10.1016/j.ijbiomac.2019.05.132] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 05/20/2019] [Accepted: 05/21/2019] [Indexed: 11/22/2022]
Abstract
Acetylcholinesterase (AchE) serves as an important target for Alzheimer's disease. Salvia miltiorrhiza has been used to treat cardiovascular disease for hundreds of years. However, the interaction between S. miltiorrhiza and AchE is still inadequate. Herein, an integrated method including molecular docking and experimental studies was employed to investigate the interaction. Consequently, some components were screened as potent AchE inhibitors by in silico and in vitro. Among them, miltirone (MT) and salvianolic acid A (SAA) reversibly inhibited AchE in a mixed-competitive manner. Fluorescence data revealed that SAA and salvianolic acid C (SAC) strongly quenched the intrinsic fluorescence of AchE through a static quenching mechanism, and the binding was spontaneous and dominated by hydrophobic interaction inferred by the thermodynamic parameters. The synchronous and ANS-binding fluorescence spectra suggested that SAA and SAC could bind to the enzyme and induce its conformation changes of secondary structures, which was further confirmed by Fourier transform infrared spectra. Meanwhile, molecular docking presented the probable binding modes of inhibitors to AchE and highlighted the key role of hydrophobic interaction and hydrogen bonds for the stability of docking complex. These findings put more insights into understanding the interaction of S. miltiorrhiza chemicals and AchE, as well as Alzheimer's disease.
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16
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Tang H, Zhao D. Investigation of the interaction between salvianolic acid C and xanthine oxidase: Insights from experimental studies merging with molecular docking methods. Bioorg Chem 2019; 88:102981. [PMID: 31085372 DOI: 10.1016/j.bioorg.2019.102981] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 05/06/2019] [Accepted: 05/08/2019] [Indexed: 12/26/2022]
Abstract
Xanthine oxidase (XO) has emerged as an important target for gout. In our previous study, salvianolic acid C (SAC) was found to show potent XO inhibitory activity, whereas the interaction mechanism was still not clear. Herein, an integrated approach consisting of enzyme kinetics, multi-spectroscopic methods and molecular docking was employed to investigate the interaction between SAC and XO. Consequently, SAC exhibited a rapid and mixed-type inhibition of XO with IC50 of 5.84 ± 0.18 μM. The fluorescence data confirmed that SAC presented a strong fluorescence quenching effect through a static quenching procedure. The values of enthalpy change, entropy change and Gibbs free energy change indicated that their binding was spontaneous and driven mainly by hydrophobic interactions. Analysis of synchronous fluorescence, circular dichroism and fourier transform infrared spectra demonstrated that SAC induced conformational changes of the enzyme. Besides, further molecular docking revealed that SAC occupied the catalytic center resulting in the inhibition of XO activity. This study provides a comprehensive understanding on the interaction mechanism of SAC on XO.
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Affiliation(s)
- Hongjin Tang
- College of Biological and Chemical Engineering, Anhui Polytechnic University, Wuhu 241000, PR China.
| | - Dongsheng Zhao
- College of Pharmacy, Shandong University of Traditional Chinese Medicine, Jinan 250355, PR China
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17
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Tang H, Ma F, Zhao D, Xue Z. Exploring the effect of salvianolic acid C on α-glucosidase: Inhibition kinetics, interaction mechanism and molecular modelling methods. Process Biochem 2019. [DOI: 10.1016/j.procbio.2019.01.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Baronio CM, Baldassarre M, Barth A. Insight into the internal structure of amyloid-β oligomers by isotope-edited Fourier transform infrared spectroscopy. Phys Chem Chem Phys 2019; 21:8587-8597. [DOI: 10.1039/c9cp00717b] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Isotope-edited infrared spectroscopy reveals the structural unit of amyloid-β oligomers.
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Affiliation(s)
| | | | - Andreas Barth
- Department of Biochemistry and Biophysics
- Stockholm University
- Sweden
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19
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Valentine ML, Cardenas AE, Elber R, Baiz CR. Physiological Calcium Concentrations Slow Dynamics at the Lipid-Water Interface. Biophys J 2018; 115:1541-1551. [PMID: 30269885 DOI: 10.1016/j.bpj.2018.08.044] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 08/20/2018] [Accepted: 08/27/2018] [Indexed: 02/07/2023] Open
Abstract
Phospholipids can interact strongly with ions at physiological concentrations, and these interactions can alter membrane properties. Here, we describe the effects of calcium ions on the dynamics in phospholipid membranes. We used a combination of time-resolved ultrafast two-dimensional infrared spectroscopy and molecular dynamics simulations. We found that millimolar Ca2+ concentrations lead to slower fluctuations in the local environment at the lipid-water interface of membranes with phosphatidylserine. The effect was only observed in bilayers containing anionic phosphatidylserine; membranes composed of only zwitterionic phosphatidylcholine did not experience a slowdown. Local water dynamics were measured using the ester groups as label-free probes and were found to be up to 50% slower with 2.5 mM Ca2+. Molecular dynamics simulations show that Ca2+ primarily binds to the carboxylate group of phosphatidylserines. These findings have implications for apoptotic and diseased cells in which phosphatidylserine is exposed to extracellular calcium and for the biophysical effects of divalent cations on lipid bilayers.
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Affiliation(s)
- Mason L Valentine
- Department of Chemistry, University of Texas at Austin, Austin, Texas
| | - Alfredo E Cardenas
- Department of Chemistry, University of Texas at Austin, Austin, Texas; Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas
| | - Ron Elber
- Department of Chemistry, University of Texas at Austin, Austin, Texas; Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas
| | - Carlos R Baiz
- Department of Chemistry, University of Texas at Austin, Austin, Texas.
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20
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Mattson MA, Green TD, Lake PT, McCullagh M, Krummel AT. Elucidating Structural Evolution of Perylene Diimide Aggregates Using Vibrational Spectroscopy and Molecular Dynamics Simulations. J Phys Chem B 2018; 122:4891-4900. [DOI: 10.1021/acs.jpcb.8b02355] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Max A. Mattson
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Thomas D. Green
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Peter T. Lake
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Martin McCullagh
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Amber T. Krummel
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
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21
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Hadichegeni S, Goliaei B, Taghizadeh M, Davoodmanesh S, Taghavi F, Hashemi M. Characterization of the interaction between human serum albumin and diazinon via spectroscopic and molecular docking methods. Hum Exp Toxicol 2018; 37:959-971. [DOI: 10.1177/0960327117741752] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Human serum albumin (HSA) is a soluble blood protein which binds to small molecules (such as drugs and toxins) and transfers them within the blood circulation. In this research, the interaction of diazinon, as a toxic organophosphate, with HSA was investigated. Various biophysical methods such as fluorescence, ultraviolet–visible (UV-vis), Fourier transform infrared spectroscopy, and molecular docking were utilized to characterize the binding properties of diazinon to HSA under physiological-like condition. The UV-vis spectroscopy showed that the absorption increased and the fluorescence intensity of HSA decreased regularly with regard to the gradual increases of the concentrations of diazinon. Due to the binding constant of ( ka = 3.367 × 10+4 M−1), the α-helix structure for the first day and 35 days of incubation were obtained 66.09–55.4% and 59.99–46.48%, respectively, and their amounts in other secondary structures (β-sheet, β-anti, and random (r) coils) were increased. The molecular docking revealed a good binding site in HSA (Trp-214) for diazinon which was related to the considerable alterations in HSA secondary and tertiary structures. There is a close relationship between the secondary structure of protein and its biological activity and after 35 days of incubation, the high toxic concentrations of diazinon can make HSA to be partially unfolded and lose its structure.
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Affiliation(s)
- S Hadichegeni
- Department of Biophysics, Islamic Azad University, Science and Research Branch, Tehran, Iran
| | - B Goliaei
- Department of Biophysics, Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran
| | - M Taghizadeh
- Department of Biophysics, Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran
- Department of Cell and Molecular Biology, Faculty of Advance Science and Technology, Pharmaceutical Sciences Branch, Islamic Azad University (IAUPS), Tehran, Iran
| | - S Davoodmanesh
- Department of Biophysics, Islamic Azad University, Science and Research Branch, Tehran, Iran
| | - F Taghavi
- Department of Biophysics, Tarbiat Modares University, Tehran, Iran
| | - M Hashemi
- Department of Genetics, Islamic Azad University, Tehran Medical Branch, Tehran, Iran
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22
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Serrano AL, Lomont JP, Tu LH, Raleigh DP, Zanni MT. A Free Energy Barrier Caused by the Refolding of an Oligomeric Intermediate Controls the Lag Time of Amyloid Formation by hIAPP. J Am Chem Soc 2017; 139:16748-16758. [PMID: 29072444 DOI: 10.1021/jacs.7b08830] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Transiently populated oligomers formed en route to amyloid fibrils may constitute the most toxic aggregates associated with many amyloid-associated diseases. Most nucleation theories used to describe amyloid aggregation predict low oligomer concentrations and do not take into account free energy costs that may be associated with structural rearrangements between the oligomer and fiber states. We have used isotope labeling and two-dimensional infrared spectroscopy to spectrally resolve an oligomeric intermediate during the aggregation of the human islet amyloid protein (hIAPP or amylin), the protein associated with type II diabetes. A structural rearrangement includes the F23G24A25I26L27 region of hIAPP, which starts from a random coil structure, evolves into ordered β-sheet oligomers containing at least 5 strands, and then partially disorders in the fibril structure. The supercritical concentration is measured to be between 150 and 250 μM, which is the thermodynamic parameter that sets the free energy of the oligomers. A 3-state kinetic model fits the experimental data, but only if it includes a concentration independent free energy barrier >3 kcal/mol that represents the free energy cost of refolding the oligomeric intermediate into the structure of the amyloid fibril; i.e., "oligomer activation" is required. The barrier creates a transition state in the free energy landscape that slows fibril formation and creates a stable population of oligomers during the lag phase, even at concentrations below the supercritical concentration. Largely missing in current kinetic models is a link between structure and kinetics. Our experiments and modeling provide evidence that protein structural rearrangements during aggregation impact the populations and kinetics of toxic oligomeric species.
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Affiliation(s)
- Arnaldo L Serrano
- Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Justin P Lomont
- Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Ling-Hsien Tu
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11790, United States
| | - Daniel P Raleigh
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11790, United States
| | - Martin T Zanni
- Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
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23
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Husseini FS, Robinson D, Hunt NT, Parker AW, Hirst JD. Computing infrared spectra of proteins using the exciton model. J Comput Chem 2017; 38:1362-1375. [PMID: 27868210 PMCID: PMC5434914 DOI: 10.1002/jcc.24674] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 10/22/2016] [Accepted: 10/29/2016] [Indexed: 02/02/2023]
Abstract
The ability to compute from first principles the infrared spectrum of a protein in solution phase representing a biological system would provide a useful connection to atomistic models of protein structure and dynamics. Indeed, such calculations are a vital complement to 2DIR experimental measurements, allowing the observed signals to be interpreted in terms of detailed structural and dynamical information. In this article, we have studied nine structurally and spectroscopically well-characterized proteins, representing a range of structural types. We have simulated the equilibrium conformational dynamics in an explicit point charge water model. Using the resulting trajectories based on MD simulations, we have computed the one and two dimensional infrared spectra in the Amide I region, using an exciton approach, in which a local mode basis of carbonyl stretches is considered. The role of solvent in shifting the Amide I band (by 30 to 50 cm-1 ) is clearly evident. Similarly, the conformational dynamics contribute to the broadening of peaks in the spectrum. The inhomogeneous broadening in both the 1D and 2D spectra reflects the significant conformational diversity observed in the simulations. Through the computed 2D cross-peak spectra, we show how different pulse schemes can provide additional information on the coupled vibrations. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Fouad S Husseini
- School of Chemistry, University of Nottingham, Nottingham, NG7 2RD, United Kingdom
| | - David Robinson
- School of Chemistry, University of Nottingham, Nottingham, NG7 2RD, United Kingdom
| | - Neil T Hunt
- Department of Physics, University of Strathclyde, SUPA, 107 Rottenrow East, Glasgow, G4 0NG, Scotland, United Kingdom
| | - Anthony W Parker
- STFC Rutherford Appleton Laboratory, Central Laser Facility, Harwell Campus, Didcot, OX11 0QX, United Kingdom
| | - Jonathan D Hirst
- School of Chemistry, University of Nottingham, Nottingham, NG7 2RD, United Kingdom
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24
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Synthesis, spectroscopic and molecular docking studies of imidazolium and pyridinium based ionic liquids with HSA as potential antimicrobial agents. J Mol Struct 2017. [DOI: 10.1016/j.molstruc.2017.02.079] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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25
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Thirumuruganandham SP, Gómez EA, Lakshmanan S, Hamblin MR. Terahertz Frequency Spectroscopy to Determine Cold Shock Protein Stability upon Solvation and Evaporation - A Molecular Dynamics Study. IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY 2017; 7:131-143. [PMID: 30881732 PMCID: PMC6419770 DOI: 10.1109/tthz.2016.2637380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Infrared (IR) and Terahertz (THz) spectroscopy simulations were carried out using CHARMM35b2 to determine protein stability. The stabilities of three bacterial cold shock proteins (Csps) originating from mesophiles, thermophiles and hyper- thermophiles respectively were investigated in this study. The three different Csps were investigated by Normal-Mode analysis and Molecular Dynamics simulation of THz spectra using the Hessian matrix for solvated systems, interpreted in the harmonic approximation at optimum near-melting temperatures of each homologue, by incorporating differences in the hydrous and anhydrous states of the Csps. The results show slight variations in the large scale protein motion. However, the IR spectra of Csps observed at the low frequency saddle surface region, clearly distinguishes the thermophilic and mesophilic proteins based on their stability. Further studies on protein stability employing low-frequency collective modes have the potential to reveal functionally important conformational changes that are biologically significant.
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Affiliation(s)
| | - Edgar A Gómez
- Programa de Física, Universidad del Quindío, Armenia, Colombia
| | - Shanmugamurthy Lakshmanan
- Department of Dermatology, Harvard Medical School, Boston, MA 02114, USA
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Michael R Hamblin
- Department of Dermatology, Harvard Medical School, Boston, MA 02114, USA
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA
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26
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Cunha AV, Bondarenko AS, Jansen TLC. Assessing Spectral Simulation Protocols for the Amide I Band of Proteins. J Chem Theory Comput 2016; 12:3982-92. [PMID: 27348022 DOI: 10.1021/acs.jctc.6b00420] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We present a benchmark study of spectral simulation protocols for the amide I band of proteins. The amide I band is widely used in infrared spectroscopy of proteins due to the large signal intensity, high sensitivity to hydrogen bonding, and secondary structural motifs. This band has, thus, proven valuable in many studies of protein structure-function relationships. We benchmark spectral simulation protocols using two common force fields in combination with several electrostatic mappings and coupling models. The results are validated against experimental linear absorption and two-dimensional infrared spectroscopy for three well-studied proteins. We find two-dimensional infrared spectroscopy to be much more sensitive to the simulation protocol than linear absorption and report on the best simulation protocols. The findings demonstrate that there is still room for ideas to improve the existing models for the amide I band of proteins.
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Affiliation(s)
- Ana V Cunha
- Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Anna S Bondarenko
- Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Thomas L C Jansen
- Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
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27
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Edington SC, Flanagan JC, Baiz CR. An Empirical IR Frequency Map for Ester C═O Stretching Vibrations. J Phys Chem A 2016; 120:3888-96. [DOI: 10.1021/acs.jpca.6b02887] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sean C. Edington
- Department
of Chemistry, University of Texas at Austin, 105 E. 24th St. Stop A5300, Austin, Texas 78712-1224, United States
| | - Jennifer C. Flanagan
- Department
of Chemistry, University of Texas at Austin, 105 E. 24th St. Stop A5300, Austin, Texas 78712-1224, United States
| | - Carlos R. Baiz
- Department
of Chemistry, University of Texas at Austin, 105 E. 24th St. Stop A5300, Austin, Texas 78712-1224, United States
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28
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Reppert M, Tokmakoff A. Computational Amide I 2D IR Spectroscopy as a Probe of Protein Structure and Dynamics. Annu Rev Phys Chem 2016; 67:359-86. [DOI: 10.1146/annurev-physchem-040215-112055] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Mike Reppert
- Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637;
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Andrei Tokmakoff
- Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637;
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29
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Bondarenko AS, Jansen TLC. Application of two-dimensional infrared spectroscopy to benchmark models for the amide I band of proteins. J Chem Phys 2016; 142:212437. [PMID: 26049457 DOI: 10.1063/1.4919716] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
In this paper, we present a novel benchmarking method for validating the modelling of vibrational spectra for the amide I region of proteins. We use the linear absorption spectra and two-dimensional infrared spectra of four experimentally well-studied proteins as a reference and test nine combinations of molecular dynamics force fields, vibrational frequency mappings, and coupling models. We find that two-dimensional infrared spectra provide a much stronger test of the models than linear absorption does. The best modelling approach in the present study still leaves significant room for future improvement. The presented benchmarking scheme, thus, provides a way of validating future protocols for modelling the amide I band in proteins.
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Affiliation(s)
- Anna S Bondarenko
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Thomas L C Jansen
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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30
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Reppert M, Roy AR, Tokmakoff A. Isotope-enriched protein standards for computational amide I spectroscopy. J Chem Phys 2016; 142:125104. [PMID: 25833611 DOI: 10.1063/1.4915271] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a systematic isotope labeling study of the protein G mutant NuG2b as a step toward the production of reliable, structurally stable, experimental standards for amide I infrared spectroscopic simulations. By introducing isotope enriched amino acids into a minimal growth medium during bacterial expression, we induce uniform labeling of the amide bonds following specific amino acids, avoiding the need for chemical peptide synthesis. We use experimental data to test several common amide I frequency maps and explore the influence of various factors on map performance. Comparison of the predicted absorption frequencies for the four maps tested with empirical assignments to our experimental spectra yields a root-mean-square error of 6-12 cm(-1), with outliers of at least 12 cm(-1) in all models. This means that the predictions may be useful for predicting general trends such as changes in hydrogen bonding configuration; however, for finer structural constraints or absolute frequency assignments, the models are unreliable. The results indicate the need for careful testing of existing literature maps and shed light on possible next steps for the development of quantitative spectral maps.
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Affiliation(s)
- Mike Reppert
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Anish R Roy
- Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
| | - Andrei Tokmakoff
- Department of Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
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31
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Baiz CR, Tokmakoff A. Structural disorder of folded proteins: isotope-edited 2D IR spectroscopy and Markov state modeling. Biophys J 2016; 108:1747-1757. [PMID: 25863066 DOI: 10.1016/j.bpj.2014.12.061] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 12/05/2014] [Accepted: 12/19/2014] [Indexed: 01/14/2023] Open
Abstract
The conformational heterogeneity of the N-terminal domain of the ribosomal protein L9 (NTL91-39) in its folded state is investigated using isotope-edited two-dimensional infrared spectroscopy. Backbone carbonyls are isotope-labeled ((13)C=(18)O) at five selected positions (V3, V9, V9G13, G16, and G24) to provide a set of localized spectroscopic probes of the structure and solvent exposure at these positions. Structural interpretation of the amide I line shapes is enabled by spectral simulations carried out on structures extracted from a recent Markov state model. The V3 label spectrum indicates that the β-sheet contacts between strands I and II are well folded with minimal disorder. The V9 and V9G13 label spectra, which directly probe the hydrogen-bond contacts across the β-turn, show significant disorder, indicating that molecular dynamics simulations tend to overstabilize ideally folded β-turn structures in NTL91-39. In addition, G24-label spectra provide evidence for a partially disordered α-helix backbone that participates in hydrogen bonding with the surrounding water.
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Affiliation(s)
- Carlos R Baiz
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois
| | - Andrei Tokmakoff
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois.
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32
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Torii H, Kawanaka M. Secondary Structure Dependence and Hydration Effect of the Infrared Intensity of the Amide II Mode of Peptide Chains. J Phys Chem B 2015; 120:1624-34. [DOI: 10.1021/acs.jpcb.5b08258] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Hajime Torii
- Department
of Chemistry, Faculty of Education, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan
- Department
of Optoelectronics and Nanostructure Science, Graduate School of Science
and Technology, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan
| | - Megumi Kawanaka
- Department
of Chemistry, Faculty of Education, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan
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33
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Torii H. Amide I Vibrational Properties Affected by Hydrogen Bonding Out-of-Plane of the Peptide Group. J Phys Chem Lett 2015; 6:727-733. [PMID: 26262494 DOI: 10.1021/acs.jpclett.5b00004] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The amide I vibrational properties of a peptide-water complex in various intermolecular configurations are analyzed theoretically to see whether a water molecule with a weak out-of-plane hydrogen bond really induces a large low-frequency shift. It is shown that the frequency shift strongly depends on the C═O···H angle, with a larger low-frequency shift as the C═O···H becomes more bent, suggesting that the so-called hydrated helix with a rather low amide I frequency has an additional water molecule located out-of-plane of the peptide group as compared with a typical α-helix. The infrared intensity also depends on the angular position of water. A new model parameter set (that can be combined with molecular dynamics) is developed for a more correct representation of the hydration-induced frequency shift. The question regarding the scalar and vectorial nature of the molecular properties related to the frequency shift is also discussed.
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Affiliation(s)
- Hajime Torii
- Department of Chemistry, Faculty of Education, and Department of Optoelectronics and Nanostructure Science, Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan
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34
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Baiz CR, Lin YS, Peng CS, Beauchamp KA, Voelz VA, Pande VS, Tokmakoff A. A molecular interpretation of 2D IR protein folding experiments with Markov state models. Biophys J 2014; 106:1359-70. [PMID: 24655511 DOI: 10.1016/j.bpj.2014.02.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 01/28/2014] [Accepted: 02/03/2014] [Indexed: 11/24/2022] Open
Abstract
The folding mechanism of the N-terminal domain of ribosomal protein L9 (NTL91-39) is studied using temperature-jump (T-jump) amide I' two-dimensional infrared (2D IR) spectroscopy in combination with spectral simulations based on a Markov state model (MSM) built from millisecond-long molecular dynamics trajectories. The results provide evidence for a compact well-structured folded state and a heterogeneous fast-exchanging denatured state ensemble exhibiting residual secondary structure. The folding rate of 26.4 μs(-1) (at 80°C), extracted from the T-jump response of NTL91-39, compares favorably with the 18 μs(-1) obtained from the MSM. Structural decomposition of the MSM and analysis along the folding coordinate indicates that helix-formation nucleates the global folding. Simulated difference spectra, corresponding to the global folding transition of the MSM, are in qualitative agreement with measured T-jump 2D IR spectra. The experiments demonstrate the use of T-jump 2D IR spectroscopy as a valuable tool for studying protein folding, with direct connections to simulations. The results suggest that in addition to predicting the correct native structure and folding time constant, molecular dynamics simulations carried out with modern force fields provide an accurate description of folding mechanisms in small proteins.
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Affiliation(s)
- Carlos R Baiz
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Yu-Shan Lin
- Department of Chemistry, Stanford University, Stanford, California
| | - Chunte Sam Peng
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | | | - Vincent A Voelz
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania
| | - Vijay S Pande
- Department of Chemistry, Stanford University, Stanford, California; Biophysics Program, Stanford University, Stanford, California; Department of Structural Biology, Stanford University, Stanford, California
| | - Andrei Tokmakoff
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts.
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35
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Guerrero P, Garrido T, Leceta I, de la Caba K. Films based on proteins and polysaccharides: Preparation and physical–chemical characterization. Eur Polym J 2013. [DOI: 10.1016/j.eurpolymj.2013.08.014] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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36
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Reppert M, Tokmakoff A. Electrostatic frequency shifts in amide I vibrational spectra: direct parameterization against experiment. J Chem Phys 2013; 138:134116. [PMID: 23574217 DOI: 10.1063/1.4798938] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The interpretation of protein amide I infrared spectra has been greatly assisted by the observation that the vibrational frequency of a peptide unit reports on its local electrostatic environment. However, the interpretation of spectra remains largely qualitative due to a lack of direct quantitative connections between computational models and experimental data. Here, we present an empirical parameterization of an electrostatic amide I frequency map derived from the infrared absorption spectra of 28 dipeptides. The observed frequency shifts are analyzed in terms of the local electrostatic potential, field, and field gradient, evaluated at sites near the amide bond in molecular dynamics simulations. We find that the frequency shifts observed in experiment correlate very well with the electric field in the direction of the C=O bond evaluated at the position of the amide oxygen atom. A linear best-fit mapping between observed frequencies and electric field yield sample standard deviations of 2.8 and 3.7 cm(-1) for the CHARMM27 and OPLS-AA force fields, respectively, and maximum deviations (within our data set) of 9 cm(-1). These results are discussed in the broader context of amide I vibrational models and the effort to produce quantitative agreement between simulated and experimental absorption spectra.
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Affiliation(s)
- Mike Reppert
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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37
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Prigozhin MB, Gruebele M. Microsecond folding experiments and simulations: a match is made. Phys Chem Chem Phys 2013; 15:3372-88. [PMID: 23361200 PMCID: PMC3632410 DOI: 10.1039/c3cp43992e] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
For the past two decades, protein folding experiments have been speeding up from the second or millisecond time scale to the microsecond time scale, and full-atom simulations have been extended from the nanosecond to the microsecond and even millisecond time scale. Where the two meet, it is now possible to compare results directly, allowing force fields to be validated and refined, and allowing experimental data to be interpreted in atomistic detail. In this perspective we compare recent experiments and simulations on the microsecond time scale, pointing out the progress that has been made in determining native structures from physics-based simulations, refining experiments and simulations to provide more quantitative underlying mechanisms, and tackling the problems of multiple reaction coordinates, downhill folding, and complex underlying structure of unfolded or misfolded states.
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Affiliation(s)
- M. B. Prigozhin
- Department of Chemistry, Center for Biophsyics and Computational Biology, 600 South Mathews Ave. Box 5–6, Urbana IL 61801, USA
| | - M. Gruebele
- Department of Chemistry, Center for Biophsyics and Computational Biology, 600 South Mathews Ave. Box 5–6, Urbana IL 61801, USA
- Department of Physics, Center for Biophsyics and Computational Biology, 600 South Mathews Ave. Box 5–6, Urbana IL 61801, USA
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38
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Baiz CR, Reppert M, Tokmakoff A. Amide I Two-Dimensional Infrared Spectroscopy: Methods for Visualizing the Vibrational Structure of Large Proteins. J Phys Chem A 2012; 117:5955-61. [DOI: 10.1021/jp310689a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Carlos R. Baiz
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
02139, United States
| | - Mike Reppert
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
02139, United States
| | - Andrei Tokmakoff
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
02139, United States
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39
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Roy S, Lessing J, Meisl G, Ganim Z, Tokmakoff A, Knoester J, Jansen TLC. Solvent and conformation dependence of amide I vibrations in peptides and proteins containing proline. J Chem Phys 2012; 135:234507. [PMID: 22191886 DOI: 10.1063/1.3665417] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a mixed quantum-classical model for studying the amide I vibrational dynamics (predominantly CO stretching) in peptides and proteins containing proline. There are existing models developed for determining frequencies of and couplings between the secondary amide units. However, these are not applicable to proline because this amino acid has a tertiary amide unit. Therefore, a new parametrization is required for infrared-spectroscopic studies of proteins that contain proline, such as collagen, the most abundant protein in humans and animals. Here, we construct the electrostatic and dihedral maps accounting for solvent and conformation effects on frequency and coupling for the proline unit. We examine the quality and the applicability of these maps by carrying out spectral simulations of a number of peptides with proline in D(2)O and compare with experimental observations.
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Affiliation(s)
- Santanu Roy
- Center for Theoretical Physics and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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40
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Karjalainen EL, Ersmark T, Barth A. Optimization of Model Parameters for Describing the Amide I Spectrum of a Large Set of Proteins. J Phys Chem B 2012; 116:4831-42. [DOI: 10.1021/jp301095v] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Eeva-Liisa Karjalainen
- Department of Biochemistry and Biophysics,
Arrhenius
Laboratories of Natural Sciences, Stockholm University, SE-106 91, Sweden
| | - Tore Ersmark
- Department of Biochemistry and Biophysics,
Arrhenius
Laboratories of Natural Sciences, Stockholm University, SE-106 91, Sweden
| | - Andreas Barth
- Department of Biochemistry and Biophysics,
Arrhenius
Laboratories of Natural Sciences, Stockholm University, SE-106 91, Sweden
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41
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Lee H, Lee G, Jeon J, Cho M. Vibrational spectroscopic determination of local solvent electric field, solute-solvent electrostatic interaction energy, and their fluctuation amplitudes. J Phys Chem A 2011; 116:347-57. [PMID: 22087732 DOI: 10.1021/jp209709e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
IR probes have been extensively used to monitor local electrostatic and solvation dynamics. Particularly, their vibrational frequencies are highly sensitive to local solvent electric field around an IR probe. Here, we show that the experimentally measured vibrational frequency shifts can be inversely used to determine local electric potential distribution and solute-solvent electrostatic interaction energy. In addition, the upper limits of their fluctuation amplitudes are estimated by using the vibrational bandwidths. Applying this method to fully deuterated N-methylacetamide (NMA) in D(2)O and examining the solvatochromic effects on the amide I' and II' mode frequencies, we found that the solvent electric potential difference between O(═C) and D(-N) atoms of the peptide bond is about 5.4 V, and thus, the approximate solvent electric field produced by surrounding water molecules on the NMA is 172 MV/cm on average if the molecular geometry is taken into account. The solute-solvent electrostatic interaction energy is estimated to be -137 kJ/mol, by considering electric dipole-electric field interaction. Furthermore, their root-mean-square fluctuation amplitudes are as large as 1.6 V, 52 MV/cm, and 41 kJ/mol, respectively. We found that the water electric potential on a peptide bond is spatially nonhomogeneous and that the fluctuation in the electrostatic peptide-water interaction energy is about 10 times larger than the thermal energy at room temperature. This indicates that the peptide-solvent interactions are indeed important for the activation of chemical reactions in aqueous solution.
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Affiliation(s)
- Hochan Lee
- Department of Chemistry and Research Institute for Natural Sciences, Korea University, Seoul 136-701, Korea
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42
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Zhang G, Wang L, Fu P, Hu M. Mechanism and conformational studies of farrerol binding to bovine serum albumin by spectroscopic methods. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2011; 82:424-431. [PMID: 21831703 DOI: 10.1016/j.saa.2011.07.073] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 07/05/2011] [Accepted: 07/13/2011] [Indexed: 05/31/2023]
Abstract
The mechanism and conformational changes of farrerol binding to bovine serum albumin (BSA) were studied by spectroscopic methods including fluorescence quenching technique, UV-vis absorption, circular dichroism (CD) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy under simulative physiological conditions. The results of fluorescence titration revealed that farrerol could strongly quench the intrinsic fluorescence of BSA through a static quenching procedure. The thermodynamic parameters enthalpy change and entropy change for the binding were calculated to be -29.92 kJ mol(-1) and 5.06 J mol(-1) K(-1) according to the van't Hoff equation, which suggested that the both hydrophobic interactions and hydrogen bonds play major role in the binding of farrerol to BSA. The binding distance r deduced from the efficiency of energy transfer was 3.11 nm for farrerol-BSA system. The displacement experiments of site markers and the results of fluorescence anisotropy showed that warfarin and farrerol shared a common binding site I corresponding to the subdomain IIA of BSA. Furthermore, the studies of synchronous fluorescence, CD and FT-IR spectroscopy showed that the binding of farrerol to BSA induced conformational changes in BSA.
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Affiliation(s)
- Guowen Zhang
- State Key Laboratory of Food Science and Technology, Nanchang University, 235, Nanjing East Road, Nanchang 330047, Jiangxi, China.
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43
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Abstract
The toxic free radical NO (nitric oxide) has diverse biological roles in eukaryotes and bacteria, being involved in signalling, vasodilation, blood clotting and immunity, and as an intermediate in microbial denitrification. The predominant biological mechanism of detecting NO is through the formation of iron nitrosyl complexes, although this is a deleterious process for other iron-containing enzymes. We have previously applied techniques such as UV–visible and EPR spectroscopy to the analysis of protein Fe–NO complex formation in order to study how NO controls the activity of the bacterial transcriptional regulators NorR and NsrR. These studies have analysed NO-dependent biological activity both in vitro and in vivo using diverse biochemical, molecular and spectroscopic methods. Recently, we have applied ultrafast 2D-IR (two-dimensional IR) spectroscopy to the analysis of NO–protein interactions using Mb (myoglobin) and Cc (cytochrome c) as model haem proteins. The ultrafast fluctuations of Cc and Mb show marked differences, indicating altered flexibility of the haem pockets. We have extended this analysis to bacterial catalase enzymes that are known to play a role in the nitrosative stress response by detoxifying peroxynitrite. The first 2D-IR analysis of haem nitrosylation and perspectives for the future are discussed.
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44
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Goj A, Bittner ER. Mixed quantum classical simulations of excitons in peptide helices. J Chem Phys 2011; 134:205103. [PMID: 21639483 DOI: 10.1063/1.3592155] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Anne Goj
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, USA
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45
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Wang L, Middleton CT, Zanni MT, Skinner JL. Development and validation of transferable amide I vibrational frequency maps for peptides. J Phys Chem B 2011; 115:3713-24. [PMID: 21405034 DOI: 10.1021/jp200745r] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Infrared (IR) spectroscopy of the amide I band has been widely utilized for the analysis of peptides and proteins. Theoretical modeling of IR spectra of proteins requires an accurate and efficient description of the amide I frequencies. In this paper, amide I frequency maps for protein backbone and side chain groups are developed from experimental spectra and vibrational lifetimes of N-methylacetamide and acetamide in different solvents. The frequency maps, along with established nearest-neighbor frequency shift and coupling schemes, are then applied to a variety of peptides in aqueous solution and reproduce experimental spectra well. The frequency maps are designed to be transferable to different environments; therefore, they can be used for heterogeneous systems, such as membrane proteins.
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Affiliation(s)
- L Wang
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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46
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Baiz CR, Kubarych KJ, Geva E. Molecular theory and simulation of coherence transfer in metal carbonyls and its signature on multidimensional infrared spectra. J Phys Chem B 2011; 115:5322-39. [PMID: 21375310 DOI: 10.1021/jp109357d] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We present a general and comprehensive theoretical and computational framework for modeling ultrafast multidimensional infrared spectra of a vibrational excitonic system in liquid solution. Within this framework, we describe the dynamics of the system in terms of a quantum master equation that can account for population relaxation, dephasing, coherence-to-coherence transfer, and coherence-to-population transfer. A unique feature of our approach is that, in principle, it does not rely on any adjustable fitting parameters. More specifically, the anharmonic vibrational Hamiltonian is derived from ab initio electronic structure theory, and the system-bath coupling is expressed explicitly in terms of liquid degrees of freedom whose dynamics can be obtained via molecular dynamics simulations. The applicability of the new approach is demonstrated by employing it to model the recently observed signatures of coherence transfer in the two-dimensional spectra of dimanganese decacarbonyl in liquid cyclohexane. The results agree well with experiment and shed new light on the nature of the molecular interactions and dynamics underlying the spectra and the interplay between dark and bright states, their level of degeneracy, and the nature of their interactions with the solvent.
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Affiliation(s)
- Carlos R Baiz
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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47
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Dijkstra AG, Jansen TLC, Knoester J. Modeling the vibrational dynamics and nonlinear infrared spectra of coupled amide I and II modes in peptides. J Phys Chem B 2011; 115:5392-401. [PMID: 21208013 DOI: 10.1021/jp109431a] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The amide vibrational modes play an important role in energy transport and relaxation in polypeptides and proteins and provide us with spectral markers for structure and structural dynamics of these macromolecules. Here, we present a detailed model to describe the dynamic properties of the amide I and amide II modes and the resulting linear and nonlinear spectra. These two modes have large oscillator strengths, and their mutual coupling plays an important role in their relaxation. Using first-principles calculations of NMA-d(7) and a dipeptide in a fluctuating bath described by molecular dynamics simulations, we model the frequencies of the local vibrations as well as the coupling between them. Both the coherent couplings and the fluctuations induced by contact with their environment are taken into account. We apply the resulting model of interacting fluctuating oscillators to study the collective vibrations and the partially coherent transport of vibrational energy through a model α-helix. We find that the instantaneous vibrations are delocalized over a few (up to four) amide units, while the coherences in the helix survive for 0.5-1 ps, leading to coherent transport on a similar time scale.
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Affiliation(s)
- Arend G Dijkstra
- Centre for Theoretical Physics and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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48
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Paarmann A, Lima M, Chelli R, Volkov VV, Righini R, Miller RJD. Excitonic effects in two-dimensional vibrational spectra of liquid formamide. Phys Chem Chem Phys 2011; 13:11351-8. [PMID: 21573300 DOI: 10.1039/c0cp02961k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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49
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Smith AW, Lessing J, Ganim Z, Peng CS, Tokmakoff A, Roy S, Jansen TLC, Knoester J. Melting of a beta-hairpin peptide using isotope-edited 2D IR spectroscopy and simulations. J Phys Chem B 2010; 114:10913-24. [PMID: 20690697 DOI: 10.1021/jp104017h] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Isotope-edited two-dimensional infrared spectroscopy has been used to characterize the conformational heterogeneity of the beta-hairpin peptide TrpZip2 (TZ2) across its thermal unfolding transition. Four isotopologues were synthesized to probe hydrogen bonding and solvent exposure of the beta-turn (K8), the N-terminus (S1), and the midstrand region (T10 and T3T10). Isotope-shifts, 2D lineshapes, and other spectral changes to the amide I 2D IR spectra of labeled TZ2 isotopologues were observed as a function of temperature. Data were interpreted on the basis of structure-based spectroscopic modeling of conformers obtained from extensive molecular dynamics simulations. The K8 spectra reveal two unique turn geometries, the type I' beta-turn observed in the NMR structure, and a less populated disordered or bulged loop. The data indicate that structures at low temperature resemble the folded NMR structure with typical cross-strand hydrogen bonds, although with a subpopulation of misformed turns. As the temperature is raised from 25 to 85 degrees C, the fraction of population with a type I' turn increases, but the termini also fray. Hydrogen bonding contacts in the midstrand region remain at all temperatures although with increasing thermal disorder. Our data show no evidence of an extended chain or random coil state for the TZ2 peptide at any temperature. The methods demonstrated here offer an approach to characterizing conformational variation within the folded or unfolded states of proteins and peptides.
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Affiliation(s)
- Adam W Smith
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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50
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Maekawa H, Ballano G, Toniolo C, Ge NH. Linear and Two-Dimensional Infrared Spectroscopic Study of the Amide I and II Modes in Fully Extended Peptide Chains. J Phys Chem B 2010; 115:5168-82. [DOI: 10.1021/jp105527n] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Hiroaki Maekawa
- Department of Chemistry, University of California at Irvine, Irvine, California, 92697-2025
| | - Gema Ballano
- Institute of Biomolecular Chemistry, CNR, Padova Unit, Department of Chemistry, University of Padova, 35131 Padova, Italy
| | - Claudio Toniolo
- Institute of Biomolecular Chemistry, CNR, Padova Unit, Department of Chemistry, University of Padova, 35131 Padova, Italy
| | - Nien-Hui Ge
- Department of Chemistry, University of California at Irvine, Irvine, California, 92697-2025
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