1
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Lee HJ, Liu SW, Sulyok-Eiler M, Harmat V, Farkas V, Bánóczi Z, El Khabchi M, Shawn Fan HJ, Hirao K, Song JW. Neighbor effect on conformational spaces of alanine residue in azapeptides. Heliyon 2024; 10:e33159. [PMID: 39021983 PMCID: PMC11253059 DOI: 10.1016/j.heliyon.2024.e33159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 06/10/2024] [Accepted: 06/14/2024] [Indexed: 07/20/2024] Open
Abstract
The conformational properties of Alanine (Ala) residue have been investigated to understand protein folding and develop force fields. In this work, we examined the neighbor effect on the conformational spaces of Ala residue using model azapeptides, Ac-Ala-azaGly-NHMe (3, AaG), and Ac-azaGly-Ala-NHMe (4, aGA1). Ramachandran energy maps were generated by scanning (φ, ψ) dihedral angles of the Ala residues in models with the fixed dihedral angles (φ = ±90°, ψ = ±0° or ±180°) of azaGly residue using LCgau-BOP and LCgau-BOP + LRD functionals in the gas and water phases. The integral-equation-formalism polarizable continuum model (IEF-PCM) and a solvation model density (SMD) were employed to mimic the solvation effect. The most favorable conformation of Ala residue in azapeptide models is found as the polyproline II (βP), inverse γ-turn (γ'), β-sheet (βS), right-handed helix (αR), or left-handed helix (αL) depending on the conformation of neighbor azaGly residue in isolated form. Solvation methods exhibit that the Ala residue favors the βP, δR, and αR conformations regardless of its position in azapeptides 3 and 4 in water. Azapeptide 5, Ac-azaGly-Ala-NH2 (aGA2), was synthesized to evaluate the theoretical results. The X-ray structure showed that azaGly residue adopts the polyproline II (βP) and Ala residue adopts the right-handed helical (αR) structure in aGA2. The conformational preferences of aGA2 and the dimer structure of aGA2 based on the X-ray structure were examined to assess the performance of DFT functionals. In addition, the local minima of azapeptide 6, Ac-Phe-azaGly-NH2 (FaG), were compared with the previous experimental results. SMD/LCgau-BOP + LRD methods agreed well with the reported experimental results. The results suggest the importance of weak dispersion interactions, neighbor effect, and solvent influence in the conformational preferences of Ala residue in model azapeptides.
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Affiliation(s)
- Ho-Jin Lee
- Division of Natural and Mathematics Sciences, LeMoyne-Own College, Memphis, TN, 38126, USA
- Department of Natural Sciences, Southwest Tennessee Community College, Memphis, TN, 38015, USA
| | - Shi-Wei Liu
- College of Chemical Engineering, Sichuan University of Science and Engineering, Zigong City, Sichuan Province, 64300, PR China
| | - Máté Sulyok-Eiler
- Laboratory of Structural Biology and Chemistry, Institute of Chemistry, Eötvös Loránd University, Budapest, Hungary
- Hevesy György PhD School of Chemistry, Eötvös Loránd University, Budapest, Hungary
| | - Veronika Harmat
- Laboratory of Structural Biology and Chemistry, Institute of Chemistry, Eötvös Loránd University, Budapest, Hungary
- HUN-REN - ELTE Protein Modeling Research Group, Budapest, Hungary
| | - Viktor Farkas
- Laboratory of Structural Biology and Chemistry, Institute of Chemistry, Eötvös Loránd University, Budapest, Hungary
- HUN-REN - ELTE Protein Modeling Research Group, Budapest, Hungary
| | - Zoltán Bánóczi
- Department of Organic Chemistry, Institute of Chemistry, ELTE Eötvös Loránd University, 1117, Budapest, Hungary
- HUN-REN-ELTE Research Group of Peptide Chemistry, 1117, Budapest, Hungary
| | - Mouna El Khabchi
- LIMAS, Faculty of Sciences Dhar El Mahraz, University Sidi Mohamed Ben Abdallah, Fez, Morocco
| | - Hua-Jun Shawn Fan
- College of Chemical Engineering, Sichuan University of Science and Engineering, Zigong City, Sichuan Province, 64300, PR China
| | - Kimihiko Hirao
- Fukui Institute for Fundamental Chemistry, Kyoto University, Takano, Nishihiraki-cho 34-4, Sakyo-ku, Kyoto, 606-8103, Japan
| | - Jong-Won Song
- Department of Chemistry Education, Daegu University, Daegudae-ro 201, Gyeongsan-si, Gyeongsangbuk-do, 38453, Republic of Korea
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2
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Ricardi N, González-Espinoza CE, Adam S, Church JR, Schapiro I, Wesołowski TA. Embedding Nonrigid Solutes in an Averaged Environment: A Case Study on Rhodopsins. J Chem Theory Comput 2023; 19:5289-5302. [PMID: 37441785 PMCID: PMC10413860 DOI: 10.1021/acs.jctc.3c00285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/15/2023]
Abstract
Many simulation methods concerning solvated molecules are based on the assumption that the solvated species and the solvent can be characterized by some representative structures of the solute and some embedding potential corresponding to this structure. While the averaging of the solvent configurations to obtain an embedding potential has been studied in great detail, this hinges on a single solute structure representation. This assumption is re-examined and generalized for conformationally flexible solutes and tested on 4 nonrigid systems. In this generalized approach, the solute is characterized by a set of representative structures and the corresponding embedding potentials. The representative structures are identified by means of subdividing the statistical ensemble, which in this work is generated by a constant-temperature molecular dynamics simulation. The embedding potential defined in the Frozen-Density Embedding Theory is used to characterize the average effect of the solvent in each subensemble. The numerical examples concern the vertical excitation energies of protonated retinal Schiff bases in protein environments. It is comprehensively shown that subensemble averaging leads to huge computational savings compared with explicit averaging of the excitation energies in the whole ensemble while introducing only minor errors in the case of the systems examined.
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Affiliation(s)
- Niccolò Ricardi
- Department of Physical Chemistry, University of Geneva, 1205 Geneva, Switzerland
| | | | - Suliman Adam
- Fritz Haber Center for Molecular Dynamics, Hebrew University of Jerusalem Israel, 91904 Jerusalem, Israel
| | - Jonathan R Church
- Fritz Haber Center for Molecular Dynamics, Hebrew University of Jerusalem Israel, 91904 Jerusalem, Israel
| | - Igor Schapiro
- Fritz Haber Center for Molecular Dynamics, Hebrew University of Jerusalem Israel, 91904 Jerusalem, Israel
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3
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An MP2/Molecular Dynamics study of the solvent effects on the conformational equilibrium of the glycine dipeptide. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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4
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Kumar A, Toal SE, DiGuiseppi D, Schweitzer-Stenner R, Wong BM. Water-Mediated Electronic Structure of Oligopeptides Probed by Their UV Circular Dichroism, Absorption Spectra, and Time-Dependent DFT Calculations. J Phys Chem B 2020; 124:2579-2590. [PMID: 32207305 DOI: 10.1021/acs.jpcb.0c00657] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We investigate the UV absorption spectra of a series of cationic GxG peptides (where x denotes a guest residue) in aqueous solution and find that only a subset of these spectra show a strong dependence with temperature. To explore whether or not this observation reflects conformational dependencies, we carry out time-dependent density functional calculations for the polyproline II (pPII) and β-strand conformations in implicit and explicit water. We find that the calculated CD spectra for pPII can qualitatively account for the experimental spectra irrespective of the water model. The β-strand UV-CD spectra, however, require the explicit consideration of water. Contrary to conventional wisdom, we find that both the NV1 and NV2 band are the envelopes of contributions from multiple transitions that involve more than just the HOMOs and LUMOs of the peptide groups. A natural transition orbital analysis reveals that some of the transitions have a charge-transfer character. The overall manifold of transitions depends on the peptide's backbone conformation, peptide hydration, and side chain of the guest residue. Our results reveal that peptide groups, side chains, and hydration shells must be considered as an entity for a physically valid characterization of UV absorbance and circular dichroism.
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Affiliation(s)
- Anshuman Kumar
- Department of Chemical & Environmental Engineering, Materials Science & Engineering Program, Department of Chemistry, and Department of Physics & Astronomy, University of California, Riverside, Riverside, California 92521, United States
| | - Siobhan E Toal
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, New Jersey 08028, United States
| | - David DiGuiseppi
- Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | | | - Bryan M Wong
- Department of Chemical & Environmental Engineering, Materials Science & Engineering Program, Department of Chemistry, and Department of Physics & Astronomy, University of California, Riverside, Riverside, California 92521, United States
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5
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Orozco-Gonzalez Y, Manathunga M, Marín MDC, Agathangelou D, Jung KH, Melaccio F, Ferré N, Haacke S, Coutinho K, Canuto S, Olivucci M. An Average Solvent Electrostatic Configuration Protocol for QM/MM Free Energy Optimization: Implementation and Application to Rhodopsin Systems. J Chem Theory Comput 2017; 13:6391-6404. [DOI: 10.1021/acs.jctc.7b00860] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yoelvis Orozco-Gonzalez
- Université de Strasbourg-CNRS, UMR 7504, Institut de Physique et Chimie des Mateŕiaux de Strasbourg, F-67034 Strasbourg, France
- USIAS Institut d’É;tudes Avanceés, Université de Strasbourg, 5 alleé
du Geńeŕal Rouvillois, F-67083 Strasbourg, France
- Department
of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403, United States
| | - Madushanka Manathunga
- Department
of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403, United States
| | - María del Carmen Marín
- Department
of Biotechnology, Chemistry e Pharmacy, Università di Siena, via A. Moro 2, I-53100 Siena, Italy
| | - Damianos Agathangelou
- Université de Strasbourg-CNRS, UMR 7504, Institut de Physique et Chimie des Mateŕiaux de Strasbourg, F-67034 Strasbourg, France
| | - Kwang-Hwan Jung
- Department
of Life Science and Institute of Biological Interfaces, Sogang University 35 Baekbeom-Ro, Mapo-Gu, Seoul 04107, Korea
| | - Federico Melaccio
- Department
of Biotechnology, Chemistry e Pharmacy, Università di Siena, via A. Moro 2, I-53100 Siena, Italy
| | - Nicolas Ferré
- Aix-Marseille Univ, CNRS, ICR, 13013 Marseille, France
| | - Stefan Haacke
- Université de Strasbourg-CNRS, UMR 7504, Institut de Physique et Chimie des Mateŕiaux de Strasbourg, F-67034 Strasbourg, France
| | - Kaline Coutinho
- Instituto de Física, Universidade de São Paulo, 05508-090 Cidade Universitária, São Paulo/SP, Brazil
| | - Sylvio Canuto
- Instituto de Física, Universidade de São Paulo, 05508-090 Cidade Universitária, São Paulo/SP, Brazil
| | - Massimo Olivucci
- Université de Strasbourg-CNRS, UMR 7504, Institut de Physique et Chimie des Mateŕiaux de Strasbourg, F-67034 Strasbourg, France
- USIAS Institut d’É;tudes Avanceés, Université de Strasbourg, 5 alleé
du Geńeŕal Rouvillois, F-67083 Strasbourg, France
- Department
of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403, United States
- Department
of Biotechnology, Chemistry e Pharmacy, Università di Siena, via A. Moro 2, I-53100 Siena, Italy
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6
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Rubio-Martinez J, Tomas MS, Perez JJ. Effect of the solvent on the conformational behavior of the alanine dipeptide deduced from MD simulations. J Mol Graph Model 2017; 78:118-128. [PMID: 29055185 DOI: 10.1016/j.jmgm.2017.10.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 10/07/2017] [Accepted: 10/09/2017] [Indexed: 11/19/2022]
Abstract
In general, peptides do not exhibit a well-defined conformational profile in solution. However, despite the experimental blurred picture associated with their structure, compelling spectroscopic evidence shows that peptides exhibit local order. The conformational profile of a peptide is the result of a balance between intramolecular interactions between different atoms of the molecule and intermolecular interactions between atoms of the molecule and the solvent. Accordingly, the conformational profile of a peptide will change upon the properties of the solvent it is soaked. To get insight into the balance between intra- and intermolecular interactions on the conformational preferences of the peptide backbone we have studied the conformational profile of the alanine dipeptide in diverse solvents using molecular dynamics as sampling technique. Solvents studied include chloroform, methanol, dimethyl sulfoxide, water and N-methylacetamide. Different treatments of the solvent have been studied in the present work including explicit solvent molecules, a generalized Born model and using the bulk dielectric constant of the solvent. The diverse calculations identify four major conformations with different populations in the diverse solvents: the C7eq only sampled in chloroform; the C5 or extended conformation; the polyproline (PII) conformation and the right-handed α-helix conformation (αR). The results of present calculations permit to analyze how the balance between intra- and intermolecular interactions explains the populations of the diverse conformations observed.
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Affiliation(s)
- Jaime Rubio-Martinez
- Dept. of Physical Chemistry, Faculty of Chemistry, Universitat de Barcelona and the Institut de Recerca en Quimica Teorica i Computacional (IQTCUB), Mati i Franques 1-3, 08028 Barcelona, Spain
| | - M Santos Tomas
- Department of Architecture Technology, Universitat Politecnica de Catalunya, Av. Diagonal, 649, E-08028 Barcelona, Spain
| | - Juan J Perez
- Department of Chemical Engineering, Universitat Politecnica de Catalunya- Barcelona Tech, Av. Diagonal, 647, 08028 Barcelona, Spain.
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7
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Almeida GG, Cordeiro JMM, Martín ME, Aguilar MA. Conformational Changes of the Alanine Dipeptide in Water–Ethanol Binary Mixtures. J Chem Theory Comput 2016; 12:1514-24. [DOI: 10.1021/acs.jctc.5b00952] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Glauco G. Almeida
- Faculdade de Engenharia,
Universidade Estadual Paulista “Julio de Mesquita Filho″, Ilha Solteira 15385-000, Brasil
| | - João M. M. Cordeiro
- Faculdade de Engenharia,
Universidade Estadual Paulista “Julio de Mesquita Filho″, Ilha Solteira 15385-000, Brasil
| | - M. Elena Martín
- Área
de Química Física, University of Extremadura, Avda.
Elvas s/n, Edif. José Ma Viguera
Lobo, 3a planta, Badajoz 06006, Spain
| | - Manuel A. Aguilar
- Área
de Química Física, University of Extremadura, Avda.
Elvas s/n, Edif. José Ma Viguera
Lobo, 3a planta, Badajoz 06006, Spain
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8
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Dipeptides containing N-terminal threonine residues: quantum chemical structural studies on nonionic, zwitterionic and water-clustered systems. Struct Chem 2015. [DOI: 10.1007/s11224-015-0564-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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9
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Hédin F, Plattner N, Doll JD, Meuwly M. Spatial Averaging: Sampling Enhancement for Exploring Configurational Space of Atomic Clusters and Biomolecules. J Chem Theory Comput 2014; 10:4284-96. [DOI: 10.1021/ct500529w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Florent Hédin
- Department
of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Nuria Plattner
- Department
of Mathematics and Computer Science, Freie Universität Berlin, Arnimallee 6, D-14195 Berlin, Germany
| | - J. D. Doll
- Department
of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Markus Meuwly
- Department
of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
- Department
of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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10
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Omelyan I, Kovalenko A. Multiple time step molecular dynamics in the optimized isokinetic ensemble steered with the molecular theory of solvation: accelerating with advanced extrapolation of effective solvation forces. J Chem Phys 2014; 139:244106. [PMID: 24387356 DOI: 10.1063/1.4848716] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We develop efficient handling of solvation forces in the multiscale method of multiple time step molecular dynamics (MTS-MD) of a biomolecule steered by the solvation free energy (effective solvation forces) obtained from the 3D-RISM-KH molecular theory of solvation (three-dimensional reference interaction site model complemented with the Kovalenko-Hirata closure approximation). To reduce the computational expenses, we calculate the effective solvation forces acting on the biomolecule by using advanced solvation force extrapolation (ASFE) at inner time steps while converging the 3D-RISM-KH integral equations only at large outer time steps. The idea of ASFE consists in developing a discrete non-Eckart rotational transformation of atomic coordinates that minimizes the distances between the atomic positions of the biomolecule at different time moments. The effective solvation forces for the biomolecule in a current conformation at an inner time step are then extrapolated in the transformed subspace of those at outer time steps by using a modified least square fit approach applied to a relatively small number of the best force-coordinate pairs. The latter are selected from an extended set collecting the effective solvation forces obtained from 3D-RISM-KH at outer time steps over a broad time interval. The MTS-MD integration with effective solvation forces obtained by converging 3D-RISM-KH at outer time steps and applying ASFE at inner time steps is stabilized by employing the optimized isokinetic Nosé-Hoover chain (OIN) ensemble. Compared to the previous extrapolation schemes used in combination with the Langevin thermostat, the ASFE approach substantially improves the accuracy of evaluation of effective solvation forces and in combination with the OIN thermostat enables a dramatic increase of outer time steps. We demonstrate on a fully flexible model of alanine dipeptide in aqueous solution that the MTS-MD/OIN/ASFE/3D-RISM-KH multiscale method of molecular dynamics steered by effective solvation forces allows huge outer time steps up to tens of picoseconds without affecting the equilibrium and conformational properties, and thus provides a 100- to 500-fold effective speedup in comparison to conventional MD with explicit solvent. With the statistical-mechanical 3D-RISM-KH account for effective solvation forces, the method provides efficient sampling of biomolecular processes with slow and/or rare solvation events such as conformational transitions of hydrated alanine dipeptide with the mean life times ranging from 30 ps up to 10 ns for "flip-flop" conformations, and is particularly beneficial for biomolecular systems with exchange and localization of solvent and ions, ligand binding, and molecular recognition.
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Affiliation(s)
- Igor Omelyan
- National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
| | - Andriy Kovalenko
- National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
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11
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Toal S, Schweitzer-Stenner R. Local order in the unfolded state: conformational biases and nearest neighbor interactions. Biomolecules 2014; 4:725-73. [PMID: 25062017 PMCID: PMC4192670 DOI: 10.3390/biom4030725] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 06/17/2014] [Accepted: 06/20/2014] [Indexed: 12/23/2022] Open
Abstract
The discovery of Intrinsically Disordered Proteins, which contain significant levels of disorder yet perform complex biologically functions, as well as unwanted aggregation, has motivated numerous experimental and theoretical studies aimed at describing residue-level conformational ensembles. Multiple lines of evidence gathered over the last 15 years strongly suggest that amino acids residues display unique and restricted conformational preferences in the unfolded state of peptides and proteins, contrary to one of the basic assumptions of the canonical random coil model. To fully understand residue level order/disorder, however, one has to gain a quantitative, experimentally based picture of conformational distributions and to determine the physical basis underlying residue-level conformational biases. Here, we review the experimental, computational and bioinformatic evidence for conformational preferences of amino acid residues in (mostly short) peptides that can be utilized as suitable model systems for unfolded states of peptides and proteins. In this context particular attention is paid to the alleged high polyproline II preference of alanine. We discuss how these conformational propensities may be modulated by peptide solvent interactions and so called nearest-neighbor interactions. The relevance of conformational propensities for the protein folding problem and the understanding of IDPs is briefly discussed.
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Affiliation(s)
- Siobhan Toal
- Department of Chemistry, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19026, USA.
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12
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Frutos-Puerto S, Muñoz-Losa A, Martín ME, Aguilar MA. Theoretical study of the absorption and emission spectra of the anionic p-coumaric methyl ester in gas phase and in solution. COMPUT THEOR CHEM 2014. [DOI: 10.1016/j.comptc.2014.04.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Caballero D, Määttä J, Zhou AQ, Sammalkorpi M, O'Hern CS, Regan L. Intrinsic α-helical and β-sheet conformational preferences: a computational case study of alanine. Protein Sci 2014; 23:970-80. [PMID: 24753338 DOI: 10.1002/pro.2481] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 04/16/2014] [Accepted: 04/17/2014] [Indexed: 12/19/2022]
Abstract
A fundamental question in protein science is what is the intrinsic propensity for an amino acid to be in an α-helix, β-sheet, or other backbone dihedral angle ( ϕ-ψ) conformation. This question has been hotly debated for many years because including all protein crystal structures from the protein database, increases the probabilities for α-helical structures, while experiments on small peptides observe that β-sheet-like conformations predominate. We perform molecular dynamics (MD) simulations of a hard-sphere model for Ala dipeptide mimetics that includes steric interactions between nonbonded atoms and bond length and angle constraints with the goal of evaluating the role of steric interactions in determining protein backbone conformational preferences. We find four key results. For the hard-sphere MD simulations, we show that (1) β-sheet structures are roughly three and half times more probable than α-helical structures, (2) transitions between α-helix and β-sheet structures only occur when the backbone bond angle τ (NCα C) is greater than 110°, and (3) the probability distribution of τ for Ala conformations in the "bridge" region of ϕ-ψ space is shifted to larger angles compared to other regions. In contrast, (4) the distributions obtained from Amber and CHARMM MD simulations in the bridge regions are broader and have increased τ compared to those for hard sphere simulations and from high-resolution protein crystal structures. Our results emphasize the importance of hard-sphere interactions and local stereochemical constraints that yield strong correlations between ϕ-ψ conformations and τ.
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Affiliation(s)
- Diego Caballero
- Department of Physics, Yale University, New Haven, Connecticut, 06520; Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut, 06520
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14
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Influence of C-terminal residues on the structural and molecular properties of dipeptides: a theoretical study in a vacuum and implicit and explicit aqueous environments. MONATSHEFTE FUR CHEMIE 2014. [DOI: 10.1007/s00706-013-1093-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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15
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Das G, Mandal S. Quantum mechanical investigations on the role of C-terminal residue in influencing the structural features of dipeptides containing N-terminal proline. J Mol Graph Model 2014; 49:1-10. [PMID: 24468791 DOI: 10.1016/j.jmgm.2013.12.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 12/29/2013] [Accepted: 12/30/2013] [Indexed: 11/18/2022]
Abstract
This study investigates the influence of the side chain moiety of C-terminal residue on the structural and molecular properties of seven dipeptides having proline at their N-terminal positions. The C-terminal component of the dipeptides is varied with seven different combinations viz. Ala, Leu, Asp, Thr, Asn, Arg and Sec. The calculations are carried out using B3LYP/6-311++G(d,p) level of theory in gas and implicit aqueous phase. Effects of explicit aqueous environment on the dipeptide structures are also investigated for two systems. The results furnished by this DFT study provide valuable information regarding the role of the side chain groups of C-terminal residues in determining the structural features of the amide planes, values of the ψ and ф dihedrals, geometry about the α-carbon atoms, theoretical IR spectra as well as the number and type of intramolecular H-bond interactions existing in the dipeptides, and extend a fine corroboration to the earlier theoretical and experimental observations. In aqueous phase the dipeptide geometries exhibit larger values of total dipole moments, greater HOMO-LUMO energy gaps and enhanced thermodynamic stability than those in gas phase. The explicit water molecules are found to modify the geometrical parameters related to the amide planes and vibrational spectra of the dipeptides.
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Affiliation(s)
- Gunajyoti Das
- Department of Chemistry, North Eastern Hill University, Shillong 793022, India.
| | - Shilpi Mandal
- Department of Chemistry, North Eastern Hill University, Shillong 793022, India
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16
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Nearest-neighbor interactions and their influence on the structural aspects of dipeptides. Biochem Res Int 2013; 2013:939865. [PMID: 24151555 PMCID: PMC3789318 DOI: 10.1155/2013/939865] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 08/15/2013] [Indexed: 02/04/2023] Open
Abstract
In this theoretical study, the role of the side chain moiety of C-terminal residue in influencing the structural and molecular properties of dipeptides is analyzed by considering a series of seven dipeptides. The C-terminal positions of the dipeptides are varied with seven different amino acid residues, namely. Val, Leu, Asp, Ser, Gln, His, and Pyl while their N-terminal positions are kept constant with Sec residues. Full geometry optimization and vibrational frequency calculations are carried out at B3LYP/6-311++G(d,p) level in gas and aqueous phase. The stereo-electronic effects of the side chain moieties of C-terminal residues are found to influence the values of Φ and Ω dihedrals, planarity of the peptide planes, and geometry around the C7
α-carbon atoms of the dipeptides. The gas phase intramolecular H-bond combinations of the dipeptides are similar to those in aqueous phase. The theoretical vibrational spectra of the dipeptides reflect the nature of intramolecular H-bonds existing in the dipeptide structures. Solvation effects of aqueous environment are evident on the geometrical parameters related to the amide planes, dipole moments, HOMOLUMO energy gaps as well as thermodynamic stability of the dipeptides.
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17
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Das G. Structural and molecular properties of dipeptides containing N-terminal selenomethionine: a theoretical study. Struct Chem 2013. [DOI: 10.1007/s11224-013-0356-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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18
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Barata-Morgado R, Sánchez ML, Fdez. Galván I, Corchado JC, Martín ME, Muñoz-Losa A, Aguilar MA. Theoretical study of the conformational equilibrium of 1,4-dioxane in gas phase, neat liquid, and dilute aqueous solutions. Theor Chem Acc 2013. [DOI: 10.1007/s00214-013-1390-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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19
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Jiang F, Han W, Wu YD. The intrinsic conformational features of amino acids from a protein coil library and their applications in force field development. Phys Chem Chem Phys 2013; 15:3413-28. [PMID: 23385383 DOI: 10.1039/c2cp43633g] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The local conformational (φ, ψ, χ) preferences of amino acid residues remain an active research area, which are important for the development of protein force fields. In this perspective article, we first summarize spectroscopic studies of alanine-based short peptides in aqueous solution. While most studies indicate a preference for the P(II) conformation in the unfolded state over α and β conformations, significant variations are also observed. A statistical analysis from various coil libraries of high-resolution protein structures is then summarized, which gives a more coherent view of the local conformational features. The φ, ψ, χ distributions of the 20 amino acids have been obtained from a protein coil library, considering both backbone and side-chain conformational preferences. The intrinsic side-chain χ(1) rotamer preference and χ(1)-dependent Ramachandran plot can be generally understood by combining the interaction of the side-chain Cγ/Oγ atom with two neighboring backbone peptide groups. Current all-atom force fields such as AMBER ff99sb-ILDN, ff03 and OPLS-AA/L do not reproduce these distributions well. A method has been developed by combining the φ, ψ plot of alanine with the influence of side-chain χ(1) rotamers to derive the local conformational features of various amino acids. It has been further applied to improve the OPLS-AA force field. The modified force field (OPLS-AA/C) reproduces experimental (3)J coupling constants for various short peptides quite well. It also better reproduces the temperature-dependence of the helix-coil transition for alanine-based peptides. The new force field can fold a series of peptides and proteins with various secondary structures to their experimental structures. MD simulations of several globular proteins using the improved force field give significantly less deviation (RMSD) to experimental structures. The results indicate that the local conformational features from coil libraries are valuable for the development of balanced protein force fields.
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Affiliation(s)
- Fan Jiang
- Laboratory of Computational Chemistry and Drug Design, Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China
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20
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Fadda E, Woods RJ. Contribution of the empirical dispersion correction on the conformation of short alanine peptides obtained by gas-phase QM calculations. CAN J CHEM 2013; 91:859-865. [PMID: 25418993 PMCID: PMC4239032 DOI: 10.1139/cjc-2012-0542] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In this work we analyze the effect of the inclusion of an empirical dispersion term to standard DFT (DFT-D) in the prediction of the conformational energy of the alanine dipeptide (Ala2) and in assessing the relative stabilities of short polyala-nine peptides in helical conformations, i.e., α and 310 helices, from Ala4 to Ala16. The Ala2 conformational energies obtained with the dispersion-corrected GGA functional B97-D are compared to previously published high level MP2 data. Meanwhile, the B97-D performance on larger polyalanine peptides is compared to MP2, B3LYP and RHF calculations obtained at a lower level of theory. Our results show that electron correlation affects the conformational energies of short peptides with a weight that increases with the peptide length. Indeed, while the contribution of vdW forces is significant for larger peptides, in the case of Ala2 it is negligible when compared to solvent effects. Even for short peptides, the inclusion of an empirical dispersion term greatly improves accuracy of DFT methods, providing results that correlate very well with the MP2 reference at no additional computational cost.
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Affiliation(s)
- Elisa Fadda
- School of Chemistry, National University of Ireland, Galway, University Road, Galway, Ireland
| | - Robert J Woods
- School of Chemistry, National University of Ireland, Galway, University Road, Galway, Ireland; Complex Carbohydrate Research Center and Department of Chemistry, University of Georgia, Athens, GA 30602, USA
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21
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Toal S, Meral D, Verbaro D, Urbanc B, Schweitzer-Stenner R. pH-Independence of trialanine and the effects of termini blocking in short peptides: a combined vibrational, NMR, UVCD, and molecular dynamics study. J Phys Chem B 2013; 117:3689-706. [PMID: 23448349 DOI: 10.1021/jp310466b] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Several lines of evidence now well establish that unfolded peptides in general, and alanine in specific, have an intrinsic preference for the polyproline II (pPII) conformation. Investigation of local order in the unfolded state is, however, complicated by experimental limitations and the inherent dynamics of the system, which has in some cases yielded inconsistent results from different types of experiments. One method of studying these systems is the use of short model peptides, and specifically short alanine peptides, known for predominantly sampling pPII structure in aqueous solution. Recently, He et al. ( J. Am. Chem. Soc. 2012 , 134 , 1571 - 1576 ) proposed that unblocked tripeptides may not be suitable models for studying conformational propensities in unfolded peptides due to the presence of end effect, that is, electrostatic interactions between investigated amino acid residues and terminal charges. To determine whether changing the protonation states of the N- and C-termini influence the conformational manifold of the central amino acid residue in tripeptides, we have examined the pH-dependence of unblocked trialanine and the conformational preferences of alanine in the alanine dipeptide. To this end, we measured and globally analyzed amide I' band profiles and NMR J-coupling constants. We described conformational distributions as the superposition of two-dimensional Gaussian distributions assignable to specific subspaces of the Ramachandran plot. Results show that the conformational ensemble of trialanine as a whole, and the pPII content (χpPII = 0.84) in particular, remains practically unaffected by changing the protonation state. We found that compared to trialanine, the alanine dipeptide has slightly lower pPII content (χpPII = 0.74) and an ensemble more reminiscent of the unblocked Gly-Ala-Gly model peptide. In addition, a two-state thermodynamic analysis of the conformational sensitive Δε(T) and (3)J(H(N)H(α))(T) data obtained from electronic circular dichroism and H NMR spectra indicate that the free energy landscape of trialanine is similar in all protonation states. MD simulations for the investigated peptides corroborate this notion and show further that the hydration shell around unblocked trialanine is unaffected by the protonation/deprotonation of the C-terminal group. In contrast, the alanine dipeptide shows a reduced water density around the central residue as well as a less ordered hydration shell, which decreases the pPII propensity and reduces the lifetime of sampled conformations.
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Affiliation(s)
- Siobhan Toal
- Department of Chemistry, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, USA
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22
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Mandal S, Das G. Structure of dipeptides having N-terminal selenocysteine residues: a DFT study in gas and aqueous phase. J Mol Model 2013; 19:2613-23. [PMID: 23494524 DOI: 10.1007/s00894-013-1808-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 02/18/2013] [Indexed: 12/18/2022]
Abstract
Over the last few decades, dipeptides as well as their analogues have served as important model systems for the computational studies concerning the structure of protein and energetics of protein folding. Here, we present a density functional structural study on a set of seven dipeptides having N-terminal selenocysteine residues (the component in the C-terminus is varied with seven different combinations viz. Ala, Phe, Glu, Thr, Asn, Arg and Sec) in gas and simulated aqueous phase using a polarizable continuum model (PCM). The molecular geometries of the dipeptides are fully optimized at B3LYP/6-311++G(d,p) level and subsequent frequency calculations confirm them as true minima. The effects of solvation and identity of the varying C-terminal residue on the energetics, structural features of the peptide planes, values of the ψ and ф dihedrals, geometry around the α-carbon atoms and theoretically predicted vibrational spectra of the dipeptides are investigated. Two types of intramolecular H-bonds, namely N…H-N and O…H-C, are found to play important roles in influencing the planarity of the peptide planes and geometry around the α-carbon atoms of the dipeptides. The identity of the varying C-terminal residue influences the values of ф, planarity of the peptide planes and geometry around the C₇ α-carbon atoms while the solvation effects are evident on the values of bond lengths and bond angles of the amide planes.
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Affiliation(s)
- Shilpi Mandal
- Department of Chemistry, North Eastern Hill University, Shillong 793022, India
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23
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Okamoto T, Ishikawa T, Koyano Y, Yamamoto N, Kuwata K, Nagaoka M. A Minimal Implementation of the AMBER-PAICS Interface for Ab Initio FMO-QM/MM-MD Simulation. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2013. [DOI: 10.1246/bcsj.20120216] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Takuya Okamoto
- Graduate School of Information Science, Nagoya University
| | - Takeshi Ishikawa
- Division of Prion Research, Center for Emerging Infectious Disease, Gifu University
| | | | | | - Kazuo Kuwata
- Division of Prion Research, Center for Emerging Infectious Disease, Gifu University
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Investigations of dipeptide structures containing pyrrolysine as N-terminal residues: a DFT study in gas and aqueous phase. J Mol Model 2013; 19:1901-11. [PMID: 23334349 DOI: 10.1007/s00894-013-1754-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 01/02/2013] [Indexed: 10/27/2022]
Abstract
A set of six dipeptides containing pyrrolysine invariably at their N-terminal positions is studied in gas and aqueous phase using a polarizable continuum model (PCM). The molecular geometries of the dipeptides are fully optimized at B3LYP/6-31++G(d,p) level of theory and a second derivative (frequency) analysis confirms that all the optimized geometries are true minima. The effects of solvation and identity of the varying C-terminal residue on the energetics, structural features of the peptide planes, values of the ψ and ϕ dihedrals, geometry around the α-carbon atoms and theoretically predicted vibrational spectra of the dipeptides are thoroughly analyzed. Solvation effects are found to modify the gas phase conformation of the dipeptides around ψ dihedrals while the identity of the varying C-terminal residue affect the values of ϕ, planarity of the peptide planes and geometry around the α-carbon atoms. The presence or absence of three types of intramolecular H-bonds, namely O...H-N, N...H-N and O...H-C that leave noticeable signatures in the IR spectra, play crucial roles in influencing the geometry of the peptide planes and in determining the energetics of the dipeptides.
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25
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Omelyan I, Kovalenko A. Generalised canonical–isokinetic ensemble: speeding up multiscale molecular dynamics and coupling with 3D molecular theory of solvation. MOLECULAR SIMULATION 2013. [DOI: 10.1080/08927022.2012.700486] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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26
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Nakano H, Yamamoto T. Accurate and Efficient Treatment of Continuous Solute Charge Density in the Mean-Field QM/MM Free Energy Calculation. J Chem Theory Comput 2012; 9:188-203. [DOI: 10.1021/ct300831t] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Hiroshi Nakano
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Takeshi Yamamoto
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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27
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Nakano H, Yamamoto T. Variational calculation of quantum mechanical/molecular mechanical free energy with electronic polarization of solvent. J Chem Phys 2012; 136:134107. [DOI: 10.1063/1.3699234] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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