1
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Lütjohann C, Näther C, Lindhorst TK. Ready chemistry with a rare sugar: Altrobioside synthesis and analysis of conformational characteristics. Carbohydr Res 2024; 544:109228. [PMID: 39153326 DOI: 10.1016/j.carres.2024.109228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2024] [Revised: 08/05/2024] [Accepted: 08/05/2024] [Indexed: 08/19/2024]
Abstract
We describe the synthesis of the full set of the so far unknown methyl altrobiosides and the initial analysis of the conformational dynamic which occurs in some of the synthesized compounds. d-Altrose chemistry has largely been neglected as it is a rare sugar and has first to be synthesized from glucose or mannose, respectively. Nevertheless, d-altrose is particularly interesting as the energy barrier between the complementary chair conformations is rather low and therefore dynamic mixtures of conformers might occur. We describe the ready synthesis of the selectively protected altrosyl acceptors for the glycosidation from d-mannose and the altrosyl-trichloroacetimidate as useful glycosyl donor to achieve the (1 → 2), (1 → 3), (1 → 4), and (1 → 6)-α-linked altrobiosides. The diastereomeric α- and β-O-(d-altropyranosyl)-trichloroacetimidates adopt different ring conformations as analyzed by NMR and VCD spectroscopy. Also, the pyranose ring conformations of the obtained altrobiosides apparently differ from a regular 4C1 chair according to NMR analysis and are influenced by the regiochemistry of the interglycosidic linkage.
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Affiliation(s)
- Clemens Lütjohann
- Christiana Albertina University of Kiel, Otto Diels Institute of Organic Chemistry, Otto-Hahn-Platz 3-4, 24118, Kiel, Germany
| | - Christian Näther
- Christiana Albertina University of Kiel, Institute of Inorganic Chemistry, Max-Eyth-Straße 2, 24118, Kiel, Germany
| | - Thisbe K Lindhorst
- Christiana Albertina University of Kiel, Otto Diels Institute of Organic Chemistry, Otto-Hahn-Platz 3-4, 24118, Kiel, Germany.
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2
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Pöverlein MC, Hulm A, Dietschreit JCB, Kussmann J, Ochsenfeld C, Kaila VRI. QM/MM Free Energy Calculations of Long-Range Biological Protonation Dynamics by Adaptive and Focused Sampling. J Chem Theory Comput 2024; 20:5751-5762. [PMID: 38718352 DOI: 10.1021/acs.jctc.4c00199] [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: 07/10/2024]
Abstract
Water-mediated proton transfer reactions are central for catalytic processes in a wide range of biochemical systems, ranging from biological energy conversion to chemical transformations in the metabolism. Yet, the accurate computational treatment of such complex biochemical reactions is highly challenging and requires the application of multiscale methods, in particular hybrid quantum/classical (QM/MM) approaches combined with free energy simulations. Here, we combine the unique exploration power of new advanced sampling methods with density functional theory (DFT)-based QM/MM free energy methods for multiscale simulations of long-range protonation dynamics in biological systems. In this regard, we show that combining multiple walkers/well-tempered metadynamics with an extended system adaptive biasing force method (MWE) provides a powerful approach for exploration of water-mediated proton transfer reactions in complex biochemical systems. We compare and combine the MWE method also with QM/MM umbrella sampling and explore the sampling of the free energy landscape with both geometric (linear combination of proton transfer distances) and physical (center of excess charge) reaction coordinates and show how these affect the convergence of the potential of mean force (PMF) and the activation free energy. We find that the QM/MM-MWE method can efficiently explore both direct and water-mediated proton transfer pathways together with forward and reverse hole transfer mechanisms in the highly complex proton channel of respiratory Complex I, while the QM/MM-US approach shows a systematic convergence of selected long-range proton transfer pathways. In this regard, we show that the PMF along multiple proton transfer pathways is recovered by combining the strengths of both approaches in a QM/MM-MWE/focused US (FUS) scheme and reveals new mechanistic insight into the proton transfer principles of Complex I. Our findings provide a promising basis for the quantitative multiscale simulations of long-range proton transfer reactions in biological systems.
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Affiliation(s)
- Maximilian C Pöverlein
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden
| | - Andreas Hulm
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU), 81377 Munich, Germany
| | - Johannes C B Dietschreit
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU), 81377 Munich, Germany
- Department of Material Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Jörg Kussmann
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU), 81377 Munich, Germany
| | - Christian Ochsenfeld
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU), 81377 Munich, Germany
- Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany
| | - Ville R I Kaila
- Department of Biochemistry and Biophysics, Stockholm University, 10691 Stockholm, Sweden
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3
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J N C, Mallajosyula SS. Impact of Polarization on the Ring Puckering Dynamics of Hexose Monosaccharides. J Chem Inf Model 2023; 63:208-223. [PMID: 36475659 DOI: 10.1021/acs.jcim.2c01286] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Analysis of crystal structures of hexose monosaccharides α-d-mannose (α-MAN), β-d-mannose (β-MAN), α-d-glucose (α-GLC), β-d-glucose (β-GLC), α-d-galactose (α-GAL), β-d-galactose (β-GAL), α-d-altrose (α-ALT), β-d-altrose (β-ALT), α-d-idose (α-IDO), and β-d-idose (β-IDO) reveals that the monosaccharide ring adopts multiple ring conformations. These ring conformations can be broadly classified as chair, half-chair, envelope, boat, and skew-boat conformations. The ability of the monosaccharide ring to adopt multiple conformations has been closely tied with their bioactivity. However, it has been difficult to capture the dynamic information of these conformations from experimental studies. Even from simulations, capturing these different conformations is challenging because of the energy barriers involved in the transitions between the stable 4C1 and 1C4 chair forms. In this study, we analyze the influence of the polarizable force field on the ring dynamics of five major types of unsubstituted aldohexoses─glucose, mannose, galactose, altrose, and idose─and their anomers. We simulate microsecond trajectories to capture the influence of the CHARMM36 additive and polarizable carbohydrate force fields on the ring dynamics. The microsecond trajectories allow us to comment on the issues associated with equilibrium molecular dynamics simulations. Further, we use the extended system adaptive biasing force (eABF) method to compare the conformational sampling efficiencies of the additive and polarizable force fields. Our studies reveal that inclusion of polarization enhances the sampling of ring conformations and lowers the energy barriers between the 4C1 and 1C4 conformations. Overall, the CHARMM36 additive force field is observed to be rigid and favor the 4C1 conformations. Although the inclusion of polarizability results in enhancing ring flexibility, we observe sampling that does not agree with experimental results, warranting a revision of the polarizable Drude parameters.
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Affiliation(s)
- Chythra J N
- Discipline of Chemistry, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat382355, India
| | - Sairam S Mallajosyula
- Discipline of Chemistry, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat382355, India
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4
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Guvench O, Martin D, Greene M. Pyranose Ring Puckering Thermodynamics for Glycan Monosaccharides Associated with Vertebrate Proteins. Int J Mol Sci 2021; 23:473. [PMID: 35008898 PMCID: PMC8745717 DOI: 10.3390/ijms23010473] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 12/28/2021] [Accepted: 12/28/2021] [Indexed: 12/22/2022] Open
Abstract
The conformational properties of carbohydrates can contribute to protein structure directly through covalent conjugation in the cases of glycoproteins and proteoglycans and indirectly in the case of transmembrane proteins embedded in glycolipid-containing bilayers. However, there continue to be significant challenges associated with experimental structural biology of such carbohydrate-containing systems. All-atom explicit-solvent molecular dynamics simulations provide a direct atomic resolution view of biomolecular dynamics and thermodynamics, but the accuracy of the results depends on the quality of the force field parametrization used in the simulations. A key determinant of the conformational properties of carbohydrates is ring puckering. Here, we applied extended system adaptive biasing force (eABF) all-atom explicit-solvent molecular dynamics simulations to characterize the ring puckering thermodynamics of the ten common pyranose monosaccharides found in vertebrate biology (as represented by the CHARMM carbohydrate force field). The results, along with those for idose, demonstrate that the CHARMM force field reliably models ring puckering across this diverse set of molecules, including accurately capturing the subtle balance between 4C1 and 1C4 chair conformations in the cases of iduronate and of idose. This suggests the broad applicability of the force field for accurate modeling of carbohydrate-containing vertebrate biomolecules such as glycoproteins, proteoglycans, and glycolipids.
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Affiliation(s)
- Olgun Guvench
- Department of Pharmaceutical Sciences and Administration, School of Pharmacy, University of New England, 716 Stevens Avenue, Portland, ME 04103, USA; (D.M.); (M.G.)
- Graduate School of Biomedical Science and Engineering, University of Maine, 5775 Stodder Hall, Orono, ME 04469, USA
| | - Devon Martin
- Department of Pharmaceutical Sciences and Administration, School of Pharmacy, University of New England, 716 Stevens Avenue, Portland, ME 04103, USA; (D.M.); (M.G.)
- Graduate School of Biomedical Science and Engineering, University of Maine, 5775 Stodder Hall, Orono, ME 04469, USA
| | - Megan Greene
- Department of Pharmaceutical Sciences and Administration, School of Pharmacy, University of New England, 716 Stevens Avenue, Portland, ME 04103, USA; (D.M.); (M.G.)
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5
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Zou W, Tao Y, Kraka E. Describing Polytopal Rearrangements of Fluxional Molecules with Curvilinear Coordinates Derived from Normal Vibrational Modes: A Conceptual Extension of Cremer-Pople Puckering Coordinates. J Chem Theory Comput 2020; 16:3162-3193. [PMID: 32208729 DOI: 10.1021/acs.jctc.9b01274] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In this work a new curvilinear coordinate system is presented for the comprehensive description of polytopal rearrangements of N-coordinate compounds (N = 4-7) and systems containing an N-coordinate subunit. It is based on normal vibrational modes and a natural extension of the Cremer-Pople puckering coordinates ( J. Am. Chem. Soc. 1975, 97, 1354) together with the Zou-Izotov-Cremer deformation coordinates ( J. Phys. Chem. A 2011, 115, 8731) for ring structures to N-coordinate systems. We demonstrate that the new curvilinear coordinates are ideal reaction coordinates describing fluxional rearrangement pathways by revisiting the Berry pseudorotation and the lever mechanism in sulfur tetrafluoride, the Berry pseudorotation and two Muetterties' mechanisms in pentavalent compounds, the chimeric pseudorotation in iodine pentafluoride, Bailar and Ray-Dutt twists in hexacoordinate tris-chelates as well as the Bartell mechanism in iodine heptafluoride. The results of our study reveal that this dedicated curvilinear coordinate system can be applied to most coordination compounds opening new ways for the systematic modeling of fluxional processes.
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Affiliation(s)
- Wenli Zou
- Institute of Modern Physics, Northwest University, and Shaanxi Key Laboratory for Theoretical Physics Frontiers, Xi'an, Shaanxi 710127, P. R. China.,Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States
| | - Yunwen Tao
- Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States
| | - Elfi Kraka
- Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States
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6
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Alibay I, Bryce RA. Ring Puckering Landscapes of Glycosaminoglycan-Related Monosaccharides from Molecular Dynamics Simulations. J Chem Inf Model 2019; 59:4729-4741. [PMID: 31609614 DOI: 10.1021/acs.jcim.9b00529] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The conformational flexibility of the glycosaminoglycans (GAGs) is known to be key in their binding and biological function, for example in regulating coagulation and cell growth. In this work, we employ enhanced sampling molecular dynamics simulations to probe the ring conformations of GAG-related monosaccharides, including a range of acetylated and sulfated GAG residues. We first perform unbiased MD simulations of glucose anomers and the epimers glucuronate and iduronate. These calculations indicate that in some cases, an excess of 15 μs is required for adequate sampling of ring pucker due to the high energy barriers between states. However, by applying our recently developed msesMD simulation method (multidimensional swarm-enhanced sampling molecular dynamics), we were able to quantitatively and rapidly reproduce these ring pucker landscapes. From msesMD simulations, the puckering free energy profiles were then compared for 15 further monosaccharides related to GAGs; this includes to our knowledge the first simulation study of sulfation effects on β-GalNAc ring puckering. For the force field employed, we find that in general the calculated pucker free energy profiles for sulfated sugars were similar to the corresponding unsulfated profiles. This accords with recent experimental studies suggesting that variation in ring pucker of sulfated GAG residues is primarily dictated by interactions with surrounding residues rather than by intrinsic conformational preference. As an exception to this, however, we predict that 4-O-sulfation of β-GalNAc leads to reduced ring rigidity, with a significant lowering in energy of the 1C4 ring conformation; this observation may have implications for understanding the structural basis of the biological function of β-GalNAc-containing glycosaminoglycans such as dermatan sulfate.
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Affiliation(s)
- Irfan Alibay
- Division of Pharmacy and Optometry, School of Health Sciences , University of Manchester , Oxford Road , Manchester M13 9PT , U.K.,Structural Bioinformatics and Computational Biochemistry Unit, Department of Biochemistry , University of Oxford , South Parks Road , Oxford OX1 3QU , U.K
| | - Richard A Bryce
- Division of Pharmacy and Optometry, School of Health Sciences , University of Manchester , Oxford Road , Manchester M13 9PT , U.K
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7
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Nagarajan B, Sankaranarayanan NV, Desai UR. Perspective on computational simulations of glycosaminoglycans. WILEY INTERDISCIPLINARY REVIEWS. COMPUTATIONAL MOLECULAR SCIENCE 2019; 9:e1388. [PMID: 31080520 PMCID: PMC6504973 DOI: 10.1002/wcms.1388] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 07/07/2018] [Indexed: 01/06/2023]
Abstract
Glycosaminoglycans (GAGs) represent a formidable frontier for chemists, biochemists, biologists, medicinal chemists and drug delivery specialists because of massive structural complexity. GAGs are arguably the most complex, natural linear biopolymers with theoretical diversity orders of magnitude higher than proteins and nucleic acids. Yet, this diversity remains generally untapped. Computational approaches offer major routes to understand GAG structure and dynamics so as to enable novel applications of these biopolymers. In fact, computational algorithms, softwares, online tools and techniques have reached a level of sophistication that help understand atomistic details of conformational variation and protein recognition of individual GAG sequences. This review describes current approaches and challenges in computational study of GAGs. It presents a history of major findings since the earliest mention of GAGs (the 1960s), the development of parameters and force fields specific for GAGs, and the application of these tools in understanding GAG structure-function relationship. This review also presents a section on how to perform simulation of GAGs, which is directed toward researchers interested in entering this promising field with potential to impact therapy.
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Affiliation(s)
- Balaji Nagarajan
- Institute for Structural Biology, Drug Discovery and Development, Virginia Commonwealth University, Richmond,
VA 23298, USA
- Department of Medicinal Chemistry, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Nehru Viji Sankaranarayanan
- Institute for Structural Biology, Drug Discovery and Development, Virginia Commonwealth University, Richmond,
VA 23298, USA
- Department of Medicinal Chemistry, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Umesh R. Desai
- Institute for Structural Biology, Drug Discovery and Development, Virginia Commonwealth University, Richmond,
VA 23298, USA
- Department of Medicinal Chemistry, Virginia Commonwealth University, Richmond, VA 23298, USA
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8
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Tautomeric and epimeric equilibria of aldo- and ketohexoses studied by the MD simulations and QM calculations. Carbohydr Res 2019; 474:8-15. [DOI: 10.1016/j.carres.2019.01.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 01/04/2019] [Accepted: 01/09/2019] [Indexed: 11/17/2022]
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9
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Wang L, Berne BJ. Efficient sampling of puckering states of monosaccharides through replica exchange with solute tempering and bond softening. J Chem Phys 2018; 149:072306. [PMID: 30134707 DOI: 10.1063/1.5024389] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A molecular-level understanding of the structure, dynamics, and reactivity of carbohydrates is fundamental to the understanding of a range of key biological processes. The six-membered pyranose ring, a central component of biological monosaccharides and carbohydrates, has many different puckering conformations, and the conformational free energy landscape of these biologically important monosaccharides remains elusive. The puckering conformations of monosaccharides are separated by high energy barriers, which pose a great challenge for the complete sampling of these important conformations and accurate modeling of these systems. While metadynamics or umbrella sampling methods have been used to study the conformational space of monosaccharides, these methods might be difficult to generalize to other complex ring systems with more degrees of freedom. In this paper, we introduce a new enhanced sampling method for the rapid sampling over high energy barriers that combines our previously developed enhanced sampling method REST (replica exchange with solute tempering) with a bond softening (BOS) scheme that makes a chemical bond in the ring weaker as one ascends the replica ladder. We call this new method replica exchange with solute tempering and bond softening (REST/BOS). We demonstrate the superior sampling efficiency of REST/BOS over other commonly used enhanced sampling methods, including temperature replica exchange method and REST. The conformational free energy landscape of four biologically important monosaccharides, namely, α-glucose, β-glucose, β-mannose, and β-xylose, is studied using REST/BOS, and results are compared with previous experimental and theoretical studies.
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Affiliation(s)
- Lingle Wang
- Schrödinger, Inc., 120 West 45th Street, New York, New York 10036, USA
| | - B J Berne
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA
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10
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Mishra SK, Koča J. Assessing the Performance of MM/PBSA, MM/GBSA, and QM-MM/GBSA Approaches on Protein/Carbohydrate Complexes: Effect of Implicit Solvent Models, QM Methods, and Entropic Contributions. J Phys Chem B 2018; 122:8113-8121. [PMID: 30084252 DOI: 10.1021/acs.jpcb.8b03655] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Rapid and accurate binding affinity prediction of protein-carbohydrate complexes is a major challenge in glycomimetics design. Among the existing computational techniques, end-point methods have received considerable interest because of their low computational cost. However, significant obstacles remain when such methods are applied to protein-glycan complexes. This article reports the performance of end-point free-energy calculation methods: molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA), MM/generalized Born surface area (MM/GBSA), and quantum mechanics-MM/GBSA (QM-MM/GBSA) on monosaccharides bound to RSL lectin from Ralstonia solanacearum. A careful investigation of the molecular dynamics simulation length, van der Waals radii sets, GB models, QM Hamiltonians, and entropic compensation has been made, and the results are compared with the experimental binding free energies from isothermal titration calorimetry/surface plasmon resonance measurements. The binding free energies using implicit solvent methods are found to be sensitive to the simulation length, radii set, GB model, and QM Hamiltonian. A simulation length of 10 ns using the radii set mbondi provides the best agreement with the experimental values ( r2 = 0.96) by MM/PBSA. The GBHCT model is in accord with the experimental values in MM/GBSA ( r2 = 0.91) or in combination with parameterized model number 6 (PM6) ( r2 = 0.98) in QM-MM/GBSA. Out of 12 QM Hamiltonians tested, PM6, density functional theory-based tight binding (DFTB), and their variants proved to be more efficient than other semiempirical methods. These methods perform equally well in predicting both absolute and relative binding free energies.
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Affiliation(s)
- Sushil K Mishra
- Central European Institute of Technology (CEITEC), and National Centre for Biomolecular Research, Faculty of Science , Masaryk University , Kamenice-5, 625 00 Brno , Czech Republic
| | - Jaroslav Koča
- Central European Institute of Technology (CEITEC), and National Centre for Biomolecular Research, Faculty of Science , Masaryk University , Kamenice-5, 625 00 Brno , Czech Republic
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11
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Panczyk K, Plazinski W. Pyranose ring puckering in aldopentoses, ketohexoses and deoxyaldohexoses. A molecular dynamics study. Carbohydr Res 2017; 455:62-70. [PMID: 29175656 DOI: 10.1016/j.carres.2017.11.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 11/14/2017] [Accepted: 11/17/2017] [Indexed: 01/03/2023]
Abstract
Conformation of monosaccharides, including the ring shape, has for years been the subject of intensive research. Although d-aldohexopyranoses are the most extensively studied pyranoses, there also exist other groups of saccharides that contain analogous chemical system of the six-membered ring. Here we describe in details the results of the molecular dynamics-based conformational analysis concerning a series of pyranoses, namely: d-aldopentoses, d-ketohexoses as well as deoxy- (d-quinovose, l-fucose, l-rhamnose) and dideoxy- (abequose, paratose, tyvelose, digitoxose) derivatives of aldohexoses. By using the carbohydrate-dedicated GROMOS 56a6CARBO force field, we determined the conformational properties of both the lactol and hydroxymethyl groups as well as the anomeric populations for all considered compounds. The orientation of the lactol group follows the trend expected on the basis of the exo-anomeric effect for all compounds whereas the conformation of the hydroxymethyl group in d-ketohexoses is represented by the two gauche (with respect to the ring oxygen atom) rotamers. The special emphasis is put on the ring-inversion properties studied in the context of both the full chair-chair inversion and the chair-boat/skew-boat rearrangement. The calculated ring-distortion energies, compared with those obtained for regular d-aldohexopyranoses allowed for estimating the influence of particular substituents on the ring flexibility. Overall, such influence is correlated with the dimension of the substituent and its orientation but is limited to the case of the chair-chair inversion whereas the chair-to-boat/skew-boat rearrangement exhibits roughly the same properties for all pyranoses. For all d-aldopyranoses the α anomers exhibit lower ring-inversion free energies in comparison to the β anomers whereas this trend is inverted in the case of d-ketohexopyranoses.
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Affiliation(s)
- Karina Panczyk
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239, Cracow, Poland
| | - Wojciech Plazinski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239, Cracow, Poland.
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12
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Xiao R, Dane EL, Zeng J, McKnight CJ, Grinstaff MW. Synthesis of Altrose Poly-amido-saccharides with β-N-(1→2)-d-amide Linkages: A Right-Handed Helical Conformation Engineered in at the Monomer Level. J Am Chem Soc 2017; 139:14217-14223. [DOI: 10.1021/jacs.7b07405] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Ruiqing Xiao
- Department
of Chemistry and ‡Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, United States
- Department of Physiology and Biophysics and ∥Department of
Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, United States
| | - Eric L. Dane
- Department
of Chemistry and ‡Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, United States
- Department of Physiology and Biophysics and ∥Department of
Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, United States
| | - Jialiu Zeng
- Department
of Chemistry and ‡Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, United States
- Department of Physiology and Biophysics and ∥Department of
Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, United States
| | - Christopher J. McKnight
- Department
of Chemistry and ‡Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, United States
- Department of Physiology and Biophysics and ∥Department of
Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, United States
| | - Mark W. Grinstaff
- Department
of Chemistry and ‡Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, United States
- Department of Physiology and Biophysics and ∥Department of
Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, United States
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13
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Plazinski W, Plazinska A. Molecular dynamics simulations of hexopyranose ring distortion in different force fields. PURE APPL CHEM 2017. [DOI: 10.1515/pac-2016-0922] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract:The four classical, biomolecular force fields designed to study hexopyranose-based carbohydrates (GROMOS 56a6CARBO/56a6CARBO_R, GROMOS 53a6GLYC, CHARMM and GLYCAM06) have been tested in the context of ring-inversion properties. These properties were evaluated for both unfunctionalized monomers of all hexopyranoses of the d series and for residues in a chain composed of uniform units connected by α(1→4) and β(1→4) glycosidic linkages. The results indicate that the tested force fields differ in their predictions of the ring-inversion properties of both monomers and residues in a chain. The comparison with the available experimental data and with the semi-empirical Angyal scheme reveals that, at the level of monomers, GROMOS 56a6CARBO, GROMOS 53a6GLYC and CHARMM correctly reproduce the ring-inversion free energies. However, due to the lack of analogous reference data we cannot state which force field is more or less accurate in the context of ring distortion of residues in a chain. Therefore, the use of ab initio potentials is recommended in the prospective, quantitative studies on the related subject.
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Affiliation(s)
- Wojciech Plazinski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Cracow, Poland, Tel.: +48815375685, Fax: +48815375685, e-mail:
| | - Anita Plazinska
- Department of Biopharmacy, Faculty of Pharmacy, Medical University of Lublin, W. Chodzki Str., 4a, 20-093 Lublin, Poland
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14
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Effects of varying the 6-position oxidation state of hexopyranoses: a systematic comparative computational analysis of 48 monosaccharide stereoisomers. J Mol Model 2017; 23:214. [PMID: 28656484 DOI: 10.1007/s00894-017-3385-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 06/04/2017] [Indexed: 01/25/2023]
Abstract
Knowledge of multi-dimensional carbohydrate structure is essential when delineating structure-function relationships in the development of analytical techniques such as ion mobility-mass spectrometry and of carbohydrate-based therapeutics, as well as in rationally modifying the chemical and physical properties of drugs and materials based on sugars. Although monosaccharides are conventionally presumed to adopt the canonical 4C1 chair conformation, it is not well known how altering the substituent identity around the pyranose ring affects the favored conformational state. This work provides a comprehensive and systematic computational comparison of all eight aldohexose isomers in the gas phase with reduction and oxidation at the C-6 position using density functional theory (M05-2X/cc-pVTZ(-f)//B3LYP/6-31G**) to determine the conformational and anomeric preference for each sugar in the gas phase. All 6-deoxyhexose and aldohexose isomers favored the 4C1 chair conformation, while oxidation at C-6 showed a shift in equilibrium to favor the 1C4 chair for β-alluronic acid, β-guluronic acid, and β-iduronic acid. The anomeric preference was found to be significantly affected by a remote change in oxidation state, with the alternate anomer favored for several isomers. These findings provide a fundamental platform to empirically test steric and electronic effects of pyranose substituents, with the goal of formulating straightforward rules that govern carbohydrate reactivity and drive quicker, more efficient syntheses. Graphical abstract A systematic comparative conformational analysis of all eight aldohexose isomers using DFT methods (M05-2X/cc-pVTZ(-f)) reveals changes in anomeric and ring conformational preference upon reduction or oxidation at the C-6 position for several sugars.
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15
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Schutt TC, Hegde GA, Bharadwaj VS, Johns AJ, Maupin CM. Impact of Water-Dilution on the Solvation Properties of the Ionic Liquid 1-Methyltriethoxy-3-ethylimidazolium Acetate for Model Biomass Molecules. J Phys Chem B 2017; 121:843-853. [DOI: 10.1021/acs.jpcb.6b09101] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Timothy C. Schutt
- Chemical and Biological Engineering
Department, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
| | - Govind A. Hegde
- Chemical and Biological Engineering
Department, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
| | - Vivek S. Bharadwaj
- Chemical and Biological Engineering
Department, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
| | - Adam J. Johns
- Chemical and Biological Engineering
Department, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
| | - C. Mark Maupin
- Chemical and Biological Engineering
Department, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
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16
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Gaweda K, Plazinski W. Pyranose ring conformations in mono- and oligosaccharides: a combined MD and DFT approach. Phys Chem Chem Phys 2017; 19:20760-20772. [DOI: 10.1039/c7cp02920a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A two-step computational protocol is proposed to efficiently study the conformational properties of hexopyranoses with a special emphasis on their ring-inversion-properties. By applying it, the errors resulting from overestimating the contribution of the hydrogen bond-rich, low-energy structures that are not abundant in aqueous solutions are avoided.
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Affiliation(s)
- Karolina Gaweda
- Jerzy Haber Institute of Catalysis and Surface Chemistry
- Polish Academy of Sciences
- 30-239 Cracow
- Poland
| | - Wojciech Plazinski
- Jerzy Haber Institute of Catalysis and Surface Chemistry
- Polish Academy of Sciences
- 30-239 Cracow
- Poland
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17
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Lonardi A, Oborský P, Hünenberger PH. Solvent-Modulated Influence of Intramolecular Hydrogen-Bonding on the Conformational Properties of the Hydroxymethyl Group in Glucose and Galactose: A Molecular Dynamics Simulation Study. Helv Chim Acta 2016. [DOI: 10.1002/hlca.201600158] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Alice Lonardi
- Laboratory of Physical Chemistry; ETH Hönggerberg; HCI; CH-8093 Zürich Switzerland
| | - Pavel Oborský
- Laboratory of Physical Chemistry; ETH Hönggerberg; HCI; CH-8093 Zürich Switzerland
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18
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Schutt TC, Bharadwaj VS, Hegde GA, Johns AJ, Mark Maupin C. In silico insights into the solvation characteristics of the ionic liquid 1-methyltriethoxy-3-ethylimidazolium acetate for cellulosic biomass. Phys Chem Chem Phys 2016; 18:23715-26. [PMID: 27510272 DOI: 10.1039/c6cp03235d] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lignocellulosic biomass is a domestically grown, sustainable, and potentially carbon-neutral feedstock for the production of liquid fuels and other value added chemicals. This underutilized renewable feedstock has the potential to alleviate some of the current socio-economic dependence on foreign petroleum supplies while stimulating rural economies. Unfortunately, the potential of biomass has largely been underdeveloped due to the recalcitrant nature of lignocellulosic materials. Task-specific ionic liquids (ILs) have shown considerable promise as an alternative non-aqueous solvent for solvation and deconstruction of lignocellulose in the presence of metal chloride catalyst or enzymes. Recently it has been hypothesized that adding oxygen atoms to the tail of an imidazolium cation would alleviate some of the negative characteristics of the ILs by increasing mass transport properties, and decreasing IL deactivation of enzymes, while at the same time retaining favorable solvation characteristics for lignocellulose. Reported here are fully atomistic molecular dynamic simulations of 1-methyltriethoxy-3-ethylimidazolium acetate ([Me-(OEt)3-Et-IM(+)] [OAc(-)]) that elucidate promising molecular-level details pertaining to the solvation characteristics of model compounds of cellulose, and IL-induced side-chain and ring puckering conformations. It is found that the anion interactions with the saccharide induce alternate ring puckering conformations from those seen in aqueous environments (i.e.(1)C4), while the cation interactions are found to influence the conformation of the ω dihedral. These perturbations in saccharide structures are discussed in the context of their contribution to the disruption of hydrogen bonding in cellulosic architecture and their role in solvation.
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Affiliation(s)
- Timothy C Schutt
- Chemical and Biological Engineering Department, Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401, USA.
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19
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Yang M, MacKerell AD. Conformational sampling of oligosaccharides using Hamiltonian replica exchange with two-dimensional dihedral biasing potentials and the weighted histogram analysis method (WHAM). J Chem Theory Comput 2016; 11:788-99. [PMID: 25705140 DOI: 10.1021/ct500993h] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Oligosaccharides and polysaccharides exert numerous functional roles in biology through their structural diversity and conformational properties. To investigate their conformational properties using computational methods, Hamiltonian replica exchange (H-REX) combined with two-dimensional grid-based correction maps as biasing potentials (bpCMAP) significantly improves the sampling efficiency about glycosidic linkages. In the current study, we extend the application of H-REX with bpCMAP to complex saccharides and establish systematic procedures for bpCMAP construction, determination of replica distribution, and data analysis. Our main findings are that (1) the bpCMAP for each type of glycosidic linkage can be constructed from the corresponding disaccharide using gas-phase umbrella sampling simulations, (2) the replica distribution can be conveniently determined following the exact definition of the average acceptance ratio based on the assigned distribution of biasing potentials, and (3) the extracted free energy surface (or potential of mean force (PMF)) can be improved using the weighted histogram analysis method (WHAM) allowing for the inclusion of data from the excited state replicas in the calculated probability distribution. The method is applied to a branched N-glycan found on the HIV gp120 protein, and a linear N-glycan. Considering the general importance of N-glycans and the wide appreciation of the sampling problem, the present method represents an efficient procedure for the conformational sampling of complex oligo- and polysaccharides under explicit solvent conditions. More generally, the use of WHAM is anticipated to be of general utility for the calculation of PMFs from H-REX simulations in a wide range of macromolecular systems.
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Affiliation(s)
- Mingjun Yang
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland 21201, United States
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20
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Awasthi S, Kapil V, Nair NN. Sampling free energy surfaces as slices by combining umbrella sampling and metadynamics. J Comput Chem 2016; 37:1413-24. [DOI: 10.1002/jcc.24349] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 02/03/2016] [Accepted: 02/03/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Shalini Awasthi
- Department of Chemistry; Indian Institute of Technology Kanpur; Kanpur 208016 India
| | - Venkat Kapil
- Department of Chemistry; Indian Institute of Technology Kanpur; Kanpur 208016 India
| | - Nisanth N. Nair
- Department of Chemistry; Indian Institute of Technology Kanpur; Kanpur 208016 India
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21
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Ring inversion properties of 1→2, 1→3 and 1→6-linked hexopyranoses and their correlation with the conformation of glycosidic linkages. Carbohydr Res 2016; 423:43-8. [DOI: 10.1016/j.carres.2016.01.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 01/18/2016] [Accepted: 01/19/2016] [Indexed: 10/22/2022]
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22
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Plazinski W, Plazinska A, Drach M. Acyclic forms of aldohexoses and ketohexoses in aqueous and DMSO solutions: conformational features studied using molecular dynamics simulations. Phys Chem Chem Phys 2016; 18:9626-35. [DOI: 10.1039/c6cp00809g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We have performed the extensive, molecular dynamics-based simulations of aldo- and ketohexoses in their acyclic forms, analyzed their conformational behavior and linked it with the measurable quantities characteristic of cyclic tautomers.
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Affiliation(s)
- Wojciech Plazinski
- Institute of Catalysis and Surface Chemistry
- Polish Academy of Sciences
- 30-239 Cracow
- Poland
| | - Anita Plazinska
- Department of Biopharmacy
- Faculty of Pharmacy
- Medical University of Lublin
- 20-093 Lublin
- Poland
| | - Mateusz Drach
- Department of Theoretical Chemistry
- Faculty of Chemistry
- UMCS
- 20-031 Lublin
- Poland
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23
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Plazinski W, Lonardi A, Hünenberger PH. Revision of the GROMOS 56A6(CARBO) force field: Improving the description of ring-conformational equilibria in hexopyranose-based carbohydrates chains. J Comput Chem 2015; 37:354-65. [PMID: 26525424 DOI: 10.1002/jcc.24229] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 10/03/2015] [Accepted: 10/06/2015] [Indexed: 01/19/2023]
Abstract
This article describes a revised version 56A6(CARBO_R) of the GROMOS 56A6(CARBO) force field for hexopyranose-based carbohydrates. The simulated properties of unfunctionalized hexopyranoses are unaltered with respect to 56A6CARBO . In the context of both O1 -alkylated hexopyranoses and oligosaccharides, the revision stabilizes the regular (4) C1 chair for α-anomers, with the opposite effect for β-anomers. As a result, spurious ring inversions observed in α(1→4)-linked chains when using the original 56A6(CARBO) force field are alleviated. The (4) C1 chair is now the most stable conformation for all d-hexopyranose residues, irrespective of the linkage type and anomery, and of the position of the residue along the chain. The methylation of a d-hexopyranose leads to a systematic shift in the ring-inversion free energy ((4) C1 to (1) C4 ) by 7-8 kJ mol(-1), positive for the α-anomers and negative for the β-anomers, which is qualitatively compatible with the expected enhancement of the anomeric effect upon methylation at O1. The ring-inversion free energies for residues within chains are typically smaller in magnitude compared to those of the monomers, and correlate rather poorly with the latter. This suggests that the crowding of ring substituents upon chain formation alters the ring flexibility in a nonsystematic fashion. In general, the description of carbohydrate chains afforded by 56A6(CARBO_R) suggests a significant extent of ring flexibility, i.e., small but often non-negligible equilibrium populations of inverted chairs, and challenges the "textbook" picture of conformationally locked carbohydrate rings.
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Affiliation(s)
- Wojciech Plazinski
- Laboratory of Physical Chemistry, ETH Hönggerberg, HCI, Zürich, CH-8093, Switzerland.,J. Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Ul. Niezapominajek 8, Cracow, 30-239, Poland
| | - Alice Lonardi
- Laboratory of Physical Chemistry, ETH Hönggerberg, HCI, Zürich, CH-8093, Switzerland
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24
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Plazinski W, Drach M. The influence of the hexopyranose ring geometry on the conformation of glycosidic linkages investigated using molecular dynamics simulations. Carbohydr Res 2015; 415:17-27. [DOI: 10.1016/j.carres.2015.07.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 07/20/2015] [Accepted: 07/29/2015] [Indexed: 11/29/2022]
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25
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Plazinski W, Drach M. Kinetic characteristics of conformational changes in the hexopyranose rings. Carbohydr Res 2015; 416:41-50. [DOI: 10.1016/j.carres.2015.08.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 08/20/2015] [Accepted: 08/21/2015] [Indexed: 12/22/2022]
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26
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Sadhu B, Sundararajan M, Bandyopadhyay T. Selectivity of a Singly Permeating Ion in Nonselective NaK Channel: Combined QM and MD Based Investigations. J Phys Chem B 2015; 119:12783-97. [DOI: 10.1021/acs.jpcb.5b05996] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Biswajit Sadhu
- Radiation Safety Systems Division and ‡Theoretical Chemistry
Section, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Mahesh Sundararajan
- Radiation Safety Systems Division and ‡Theoretical Chemistry
Section, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Tusar Bandyopadhyay
- Radiation Safety Systems Division and ‡Theoretical Chemistry
Section, Bhabha Atomic Research Centre, Mumbai 400 085, India
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27
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Mishra SK, Calabró G, Loeffler HH, Michel J, Koča J. Evaluation of Selected Classical Force Fields for Alchemical Binding Free Energy Calculations of Protein-Carbohydrate Complexes. J Chem Theory Comput 2015; 11:3333-45. [PMID: 26575767 DOI: 10.1021/acs.jctc.5b00159] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Protein-carbohydrate recognition is crucial in many vital biological processes including host-pathogen recognition, cell-signaling, and catalysis. Accordingly, computational prediction of protein-carbohydrate binding free energies is of enormous interest for drug design. However, the accuracy of current force fields (FFs) for predicting binding free energies of protein-carbohydrate complexes is not well understood owing to technical challenges such as the highly polar nature of the complexes, anomerization, and conformational flexibility of carbohydrates. The present study evaluated the performance of alchemical predictions of binding free energies with the GAFF1.7/AM1-BCC and GLYCAM06j force fields for modeling protein-carbohydrate complexes. Mean unsigned errors of 1.1 ± 0.06 (GLYCAM06j) and 2.6 ± 0.08 (GAFF1.7/AM1-BCC) kcal·mol(-1) are achieved for a large data set of monosaccharide ligands for Ralstonia solanacearum lectin (RSL). The level of accuracy provided by GLYCAM06j is sufficient to discriminate potent, moderate, and weak binders, a goal that has been difficult to achieve through other scoring approaches. Accordingly, the protocols presented here could find useful applications in carbohydrate-based drug and vaccine developments.
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Affiliation(s)
- Sushil K Mishra
- Central European Institute of Technology (CEITEC) and National Centre for Biomolecular Research, Faculty of Science, Masaryk University , Kamenice-5, 625 00 Brno, Czech Republic
| | - Gaetano Calabró
- EaStCHEM School of Chemistry, Joseph Black Building , King's Buildings, Edinburgh EH9 3JJ, United Kingdom
| | - Hannes H Loeffler
- Scientific Computing Department, STFC Daresbury , Warrington, WA4 4AD, United Kingdom
| | - Julien Michel
- EaStCHEM School of Chemistry, Joseph Black Building , King's Buildings, Edinburgh EH9 3JJ, United Kingdom
| | - Jaroslav Koča
- Central European Institute of Technology (CEITEC) and National Centre for Biomolecular Research, Faculty of Science, Masaryk University , Kamenice-5, 625 00 Brno, Czech Republic
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28
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Iglesias-Fernández J, Raich L, Ardèvol A, Rovira C. The complete conformational free energy landscape of β-xylose reveals a two-fold catalytic itinerary for β-xylanases. Chem Sci 2015; 6:1167-1177. [PMID: 29560204 PMCID: PMC5811086 DOI: 10.1039/c4sc02240h] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2014] [Accepted: 10/27/2014] [Indexed: 01/28/2023] Open
Abstract
Unraveling the conformational catalytic itinerary of glycoside hydrolases (GHs) is a growing topic of interest in glycobiology, with major impact in the design of GH inhibitors. β-xylanases are responsible for the hydrolysis of glycosidic bonds in β-xylans, a group of hemicelluloses of high biotechnological interest that are found in plant cell walls. The precise conformations followed by the substrate during catalysis in β-xylanases have not been unambiguously resolved, with three different pathways being proposed from structural analyses. In this work, we compute the conformational free energy landscape (FEL) of β-xylose to predict the most likely catalytic itineraries followed by β-xylanases. The calculations are performed by means of ab initio metadynamics, using the Cremer-Pople puckering coordinates as collective variables. The computed FEL supports only two of the previously proposed itineraries, 2SO → [2,5B]ǂ → 5S1 and 1S3 → [4H3]ǂ → 4C1, which clearly appear in low energy regions of the FEL. Consistently, 2SO and 1S3 are conformations preactivated for catalysis in terms of free energy/anomeric charge and bond distances. The results however exclude the OE → [OS2]ǂ → B2,5 itinerary that has been recently proposed for a family 11 xylanase. Classical and ab initio QM/MM molecular dynamics simulations reveal that, in this case, the observed OE conformation has been enforced by enzyme mutation. These results add a word of caution on using modified enzymes to inform on catalytic conformational itineraries of glycoside hydrolases.
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Affiliation(s)
- Javier Iglesias-Fernández
- Departament de Química Orgànica and Institut de Química Teòrica i Computacional (IQTCUB) , Universitat de Barcelona , Martí i Franquès 1 , 08028 Barcelona , Spain .
| | - Lluís Raich
- Departament de Química Orgànica and Institut de Química Teòrica i Computacional (IQTCUB) , Universitat de Barcelona , Martí i Franquès 1 , 08028 Barcelona , Spain .
| | - Albert Ardèvol
- Department of Chemistry and Applied Biosciences , ETH Zürich , USI Campus , 6900 Lugano , Switzerland
| | - Carme Rovira
- Departament de Química Orgànica and Institut de Química Teòrica i Computacional (IQTCUB) , Universitat de Barcelona , Martí i Franquès 1 , 08028 Barcelona , Spain .
- Institució Catalana de Recerca i Estudis Avançats (ICREA) , Passeig Lluís Companys , 23 , 08018 Barcelona , Spain
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29
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Rusu VH, Baron R, Lins RD. PITOMBA: Parameter Interface for Oligosaccharide Molecules Based on Atoms. J Chem Theory Comput 2014; 10:5068-80. [DOI: 10.1021/ct500455u] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Victor H. Rusu
- Department
of Medicinal Chemistry, College of Pharmacy, and The Henry Eyring
Center for Theoretical Chemistry, The University of Utah, Salt Lake City, Utah 84112-5820, United States
- Departamento
de Química Fundamental, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE 50740-560, Brazil
| | - Riccardo Baron
- Department
of Medicinal Chemistry, College of Pharmacy, and The Henry Eyring
Center for Theoretical Chemistry, The University of Utah, Salt Lake City, Utah 84112-5820, United States
| | - Roberto D. Lins
- Departamento
de Química Fundamental, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE 50740-560, Brazil
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30
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Patel DS, Pendrill R, Mallajosyula SS, Widmalm G, MacKerell AD. Conformational properties of α- or β-(1→6)-linked oligosaccharides: Hamiltonian replica exchange MD simulations and NMR experiments. J Phys Chem B 2014; 118:2851-71. [PMID: 24552401 PMCID: PMC3979472 DOI: 10.1021/jp412051v] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Conformational sampling for a set of 10 α- or β-(1→6)-linked oligosaccharides has been studied using explicit solvent Hamiltonian replica exchange (HREX) simulations and NMR spectroscopy techniques. Validation of the force field and simulation methodology is done by comparing calculated transglycosidic J coupling constants and proton-proton distances with the corresponding NMR data. Initial calculations showed poor agreement, for example, with >3 Hz deviation of the calculated (3)J(H5,H6R) values from the experimental data, prompting optimization of the ω torsion angle parameters associated with (1→6)-linkages. The resulting force field is in overall good agreement (i.e., within ∼0.5 Hz deviation) from experimental (3)J(H5,H6R) values, although some small limitations are evident. Detailed hydrogen bonding analysis indicates that most of the compounds lack direct intramolecular H-bonds between the two monosaccharides; however, minor sampling of the O6···HO2' hydrogen bond is present in three compounds. The results verify the role of the gauche effect between O5 and O6 atoms in gluco- and manno-configured pyranosides causing the ω torsion angle to sample an equilibrium between the gt and gg rotamers. Conversely, galacto-configured pyranosides sample a population distribution in equilibrium between gt and tg rotamers, while the gg rotamer populations are minor. Water radial distribution functions suggest decreased accessibility to the O6 atom in the (1→6)-linkage as compared to the O6' atom in the nonreducing sugar. The role of bridging water molecules between two sugar moieties on the distributions of ω torsion angles in oligosaccharides is also explored.
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Affiliation(s)
- Dhilon S Patel
- Department of Pharmaceutical Sciences, University of Maryland , 20 Penn Street HSF II, Baltimore, Maryland 21201, United States
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31
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Pathak AK, Bandyopadhyay T. Unbinding free energy of acetylcholinesterase bound oxime drugs along the gorge pathway from metadynamics-umbrella sampling investigation. Proteins 2014; 82:1799-818. [PMID: 24549829 DOI: 10.1002/prot.24533] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 01/17/2014] [Accepted: 01/28/2014] [Indexed: 12/20/2022]
Abstract
Because of the pivotal role that the nerve enzyme, acetylcholinesterase plays in terminating nerve impulses at cholinergic synapses. Its active site, located deep inside a 20 Å gorge, is a vulnerable target of the lethal organophosphorus compounds. Potent reactivators of the intoxicated enzyme are nucleophiles, such as bispyridinium oxime that binds to the peripheral anionic site and the active site of the enzyme through suitable cation-π interactions. Atomic scale molecular dynamics and free energy calculations in explicit water are used to study unbinding pathways of two oxime drugs (Ortho-7 and Obidoxime) from the gorge of the enzyme. The role of enzyme-drug cation-π interactions are explored with the metadynamics simulation. The metadynamics discovered potential of mean force (PMF) of the unbinding events is refined by the umbrella sampling (US) corrections. The bidimensional free energy landscape of the metadynamics runs are further subjected to finite temperature string analysis to obtain the transition tube connecting the minima and bottlenecks of the unbinding pathway. The PMF is also obtained from US simulations using the biasing potential constructed from the transition tube and are found to be consistent with the metadynamics-US corrected results. Although experimental structural data clearly shows analogous coordination of the two drugs inside the gorge in the bound state, the PMF of the drug trafficking along the gorge pathway point, within an equilibrium free energy context, to a multistep process that differs from one another. Routes, milestones and subtlety toward the unbinding pathway of the two oximes at finite temperature are identified.
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Affiliation(s)
- Arup K Pathak
- Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Trombay, Mumbai, India
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32
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Mayes HB, Broadbelt LJ, Beckham GT. How Sugars Pucker: Electronic Structure Calculations Map the Kinetic Landscape of Five Biologically Paramount Monosaccharides and Their Implications for Enzymatic Catalysis. J Am Chem Soc 2014; 136:1008-22. [DOI: 10.1021/ja410264d] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Heather B. Mayes
- Department
of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
- National
Bioenergy Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Linda J. Broadbelt
- Department
of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Gregg T. Beckham
- National
Bioenergy Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
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33
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Plazinski W, Drach M. The dynamics of the conformational changes in the hexopyranose ring: a transition path sampling approach. RSC Adv 2014. [DOI: 10.1039/c4ra03410d] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The transition paths corresponding to the conformational rearrangements in the ring of hexapyranose (α-d- and β-d-glucose) molecules were described by applying the transition path sampling method.
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Affiliation(s)
- Wojciech Plazinski
- Institute of Catalysis and Surface Chemistry
- Polish Academy of Sciences
- 30-239 Cracow, Poland
| | - Mateusz Drach
- Department of Theoretical Chemistry
- Faculty of Chemistry
- UMCS
- 20-031 Lublin, Poland
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34
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Branduardi D, Faraldo-Gómez JD. String method for calculation of minimum free-energy paths in Cartesian space in freely-tumbling systems. J Chem Theory Comput 2013; 9:4140-4154. [PMID: 24729762 PMCID: PMC3981481 DOI: 10.1021/ct400469w] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The string method is a molecular-simulation technique that aims to calculate the minimum free-energy path of a chemical reaction or conformational transition, in the space of a pre-defined set of reaction coordinates that is typically highly dimensional. Any descriptor may be used as a reaction coordinate, but arguably the Cartesian coordinates of the atoms involved are the most unprejudiced and intuitive choice. Cartesian coordinates, however, present a non-trivial problem, in that they are not invariant to rigid-body molecular rotations and translations, which ideally ought to be unrestricted in the simulations. To overcome this difficulty, we reformulate the framework of the string method to integrate an on-the-fly structural-alignment algorithm. This approach, referred to as SOMA (String method with Optimal Molecular Alignment), enables the use of Cartesian reaction coordinates in freely tumbling molecular systems. In addition, this scheme permits the dissection of the free-energy change along the most probable path into individual atomic contributions, thus revealing the dominant mechanism of the simulated process. This detailed analysis also provides a physically-meaningful criterion to coarse-grain the representation of the path. To demonstrate the accuracy of the method we analyze the isomerization of the alanine dipeptide in vacuum and the chair-to-inverted-chair transition of β-D mannose in explicit water. Notwithstanding the simplicity of these systems, the SOMA approach reveals novel insights into the atomic mechanism of these isomerizations. In both cases, we find that the dynamics and the energetics of these processes are controlled by interactions involving only a handful of atoms in each molecule. Consistent with this result, we show that a coarse-grained SOMA calculation defined in terms of these subsets of atoms yields nearidentical minimum free-energy paths and committor distributions to those obtained via a highly-dimensional string.
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Affiliation(s)
- Davide Branduardi
- Theoretical Molecular Biophysics Group, Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, DE-60438, Frankfurt-am-Main, Germany
| | - José D. Faraldo-Gómez
- Theoretical Molecular Biophysics Group, Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, DE-60438, Frankfurt-am-Main, Germany
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35
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Oborský P, Tvaroška I, Králová B, Spiwok V. Toward an accurate conformational modeling of iduronic acid. J Phys Chem B 2013; 117:1003-9. [PMID: 23286518 DOI: 10.1021/jp3100552] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Iduronic acid (IdoA), unlike most other monosaccharides, can adopt different ring conformations, depending on the context of the molecular structure. Accurate modeling of this building block is essential for understanding the role of glycosaminoglycans and other glycoconjugates. Here, we use metadynamics to predict equilibria of (1)C(4), (4)C(1) and (2)S(O) conformations of α-L-IdoA-OMe and α-L-IdoA2S-OMe. Different schemes of scaling of atoms separated by three bonds (1-4 interaction) were tested. It was found that scaling (reduction) of 1-4 electrostatic interactions significantly changes conformational preferences toward the (4)C(1) conformation. More interestingly, scaling of 1-4 van der Waals interaction favors skew-boat conformations. This shows that a minor modification of noncovalent 1-4 interactions parameters can provide a good agreement between populations of conformers of iduronic acid in water from simulations and experiments.
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Affiliation(s)
- Pavel Oborský
- Department of Biochemistry and Microbiology, Institute of Chemical Technology, Prague, Technická 3, Prague 6 166 28, Czech Republic
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36
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Reif MM, Winger M, Oostenbrink C. Testing of the GROMOS Force-Field Parameter Set 54A8: Structural Properties of Electrolyte Solutions, Lipid Bilayers, and Proteins. J Chem Theory Comput 2013; 9:1247-1264. [PMID: 23418406 PMCID: PMC3572754 DOI: 10.1021/ct300874c] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Indexed: 11/28/2022]
Abstract
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The GROMOS 54A8 force field [Reif et al. J. Chem.
Theory
Comput.2012, 8, 3705–3723]
is the first of its kind to contain nonbonded parameters for charged
amino acid side chains that are derived in a rigorously thermodynamic
fashion, namely a calibration against single-ion hydration free energies.
Considering charged moieties in solution, the most decisive signature
of the GROMOS 54A8 force field in comparison to its predecessor 54A7
can probably be found in the thermodynamic equilibrium between salt-bridged
ion pair formation and hydration. Possible shifts in this equilibrium
might crucially affect the properties of electrolyte solutions or/and
the stability of (bio)molecules. It is therefore important to investigate
the consequences of the altered description of charged oligoatomic
species in the GROMOS 54A8 force field. The present study focuses
on examining the ability of the GROMOS 54A8 force field to accurately
model the structural properties of electrolyte solutions, lipid bilayers,
and proteins. It is found that (i) aqueous electrolytes
involving oligoatomic species (sodium acetate, methylammonium chloride,
guanidinium chloride) reproduce experimental salt activity derivatives
for concentrations up to 1.0 m (1.0-molal) very well, and good agreement
between simulated and experimental data is also reached for sodium
acetate and methylammonium chloride at 2.0 m concentration, while
not even qualitative agreement is found for sodium chloride throughout
the whole range of examined concentrations, indicating a failure of
the GROMOS 54A7 and 54A8 force-field parameter sets to correctly account
for the balance between ion–ion and ion–water binding
propensities of sodium and chloride ions; (ii) the
GROMOS 54A8 force field reproduces the liquid crystalline-like phase
of a hydrated DPPC bilayer at a pressure of 1 bar and a temperature
of 323 K, the area per lipid being in agreement with experimental
data, whereas other structural properties (volume per lipid, bilayer
thickness) appear underestimated; (iii) the secondary
structure of a range of different proteins simulated with the GROMOS
54A8 force field at pH 7 is maintained and compatible with experimental
NMR data, while, as also observed for the GROMOS 54A7 force field,
α-helices are slightly overstabilized with respect to 310-helices; (iv) with the GROMOS 54A8 force
field, the side chains of arginine, lysine, aspartate, and glutamate
residues appear slightly more hydrated and present a slight excess
of oppositely-charged solution components in their vicinity, whereas
salt-bridge formation properties between charged residues at the protein
surface, as assessed by probability distributions of interionic distances,
are largely equivalent in the GROMOS 54A7 and 54A8 force-field parameter
sets.
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Affiliation(s)
- Maria M Reif
- Institute for Molecular Modeling and Simulation, University of Natural Resources and Life Sciences, 1190 Vienna, Austria
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37
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Pol-Fachin L, Rusu VH, Verli H, Lins RD. GROMOS 53A6GLYC, an Improved GROMOS Force Field for Hexopyranose-Based Carbohydrates. J Chem Theory Comput 2012; 8:4681-90. [PMID: 26605624 DOI: 10.1021/ct300479h] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
An improved parameter set for explicit-solvent simulations of carbohydrates (referred to as GROMOS 53A6GLYC) is presented, allowing proper description of the most stable conformation of all 16 possible aldohexopyranose-based monosaccharides. This set includes refinement of torsional potential parameters associated with the determination of hexopyranose rings conformation by fitting to their corresponding quantum-mechanical profiles. Other parameters, as the rules for third and excluded neighbors, are taken directly from the GROMOS 53A6 force field. Comparisons of the herein presented parameter set to our previous version (GROMOS 45A4), the GLYCAM06 force field, and available NMR data are presented in terms of ring puckering free energies, conformational distribution of the hydroxymethyl group, and glycosidic linkage geometries for 16 selected monosaccharides and eight disaccharides. The proposed parameter modifications have shown a significant improvement for the above-mentioned quantities over the two tested force fields, while retaining full compatibility with the GROMOS 53A6 and 54A7 parameter sets for other classes of biomolecules.
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Affiliation(s)
- Laercio Pol-Fachin
- Center of Biotechnology, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Victor H Rusu
- Department of Fundamental Chemistry, Federal University of Pernambuco, Recife, PE, Brazil
| | - Hugo Verli
- Center of Biotechnology, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.,College of Pharmacy, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Roberto D Lins
- Department of Fundamental Chemistry, Federal University of Pernambuco, Recife, PE, Brazil
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38
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Xiao S, Liang H. The conformational flexibility of nucleic acid bases paired in gas phase: A Car-Parrinello molecular dynamics study. J Chem Phys 2012; 136:205102. [DOI: 10.1063/1.4720352] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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39
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Sattelle BM, Bose-Basu B, Tessier M, Woods RJ, Serianni AS, Almond A. Dependence of pyranose ring puckering on anomeric configuration: methyl idopyranosides. J Phys Chem B 2012; 116:6380-6. [PMID: 22577942 DOI: 10.1021/jp303183y] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the aldohexopyranose idose, the unique presence of three axial ring hydroxyl groups causes considerable conformational flexibility, rendering it challenging to study experimentally and an excellent model for rationalizing the relationship between puckering and anomeric configuration. Puckering in methyl α- and β-L-idopyranosides was predicted from kinetically rigorous 10 μs simulations using GLYCAM11 and three explicit water models (TIP3P, TIP4P, and TIP4P-EW). In each case, computed pyranose ring three-bond (vicinal) (1)H-(1)H spin couplings ((3)J(H,H)) trended with NMR measurements. These values, calculated puckering exchange rates and free energies, were independent of the water model. The α- and β-anomers were (1)C(4) chairs for 85 and >99% of their respective trajectories and underwent (1)C(4)→(4)C(1) exchange at rates of 20 μs(-1) and 1 μs(-1). Computed α-anomer (1)C(4)↔(4)C(1) puckering rates depended on the exocyclic C6 substituent, comparing hydroxymethyl with carboxyl from previous work. The slower kinetics and restricted pseudorotational profile of the β-anomer were caused by water occupying a cavity bounded by the anomeric 1-O-methyl and the C6 hydroxymethyl groups. This finding rationalizes the different methyl α- and β-L-idopyranoside (3)J(H,H) values. Identifying a relationship between idopyranose anomeric configuration, microsecond puckering, and water structure facilitates engineering of biologically and commercially important derivatives and underpins deciphering presently elusive structure-function relationships in the glycome.
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Affiliation(s)
- Benedict M Sattelle
- Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
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40
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Batista PR, Pandey G, Pascutti PG, Bisch PM, Perahia D, Robert CH. Free Energy Profiles along Consensus Normal Modes Provide Insight into HIV-1 Protease Flap Opening. J Chem Theory Comput 2011; 7:2348-52. [PMID: 26606609 DOI: 10.1021/ct200237u] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Describing biological macromolecular energetics from computer simulations can pose major challenges, and often necessitates enhanced conformational sampling. We describe the calculation of conformational free-energy profiles along carefully chosen collective coordinates: "consensus" normal modes, developed recently as robust alternatives to conventional normal modes. In an application to the HIV-1 protease, we obtain efficient sampling of significant flap opening movements governing inhibitor binding from relatively short simulations, in close correspondence with experimental results.
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Affiliation(s)
- Paulo R Batista
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro , 21941-902, Brasil.,CNRS Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Université Paris Sud 11 , 91405 Orsay, France.,CNRS BIMoDyM -Laboratoire de Biologie et Pharmacologie Appliquées - École Normale Supérieure de Cachan , 94235 Cachan, France
| | - Gaurav Pandey
- Indian Institute of Technology , Roorkee, 247667, India.,CNRS Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Université Paris Sud 11 , 91405 Orsay, France
| | - Pedro G Pascutti
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro , 21941-902, Brasil
| | - Paulo M Bisch
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro , 21941-902, Brasil
| | - David Perahia
- CNRS Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Université Paris Sud 11 , 91405 Orsay, France.,CNRS BIMoDyM -Laboratoire de Biologie et Pharmacologie Appliquées - École Normale Supérieure de Cachan , 94235 Cachan, France
| | - Charles H Robert
- CNRS Institut de Biochimie et Biophysique Moléculaire et Cellulaire, Université Paris Sud 11 , 91405 Orsay, France.,CNRS Laboratoire de Biochimie Théorique, Institut de Biologie Physico Chimique, Université Paris Diderot, Sorbonne Paris Cité , 75005 Paris, France
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41
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Autieri E, Chiessi E, Lonardi A, Paradossi G, Sega M. Conformation and Dynamics of Poly(N-isopropyl acrylamide) Trimers in Water: A Molecular Dynamics and Metadynamics Simulation Study. J Phys Chem B 2011; 115:5827-39. [DOI: 10.1021/jp2020929] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Emmanuel Autieri
- Department of Physics, University of Trento, via Sommarive 14, 38123 Trento, Italy
| | - Ester Chiessi
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133 Rome, Italy
| | - Alice Lonardi
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133 Rome, Italy
| | - Gaio Paradossi
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133 Rome, Italy
| | - Marcello Sega
- Department of Physics, University of Trento, via Sommarive 14, 38123 Trento, Italy
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42
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Autieri E, Sega M, Pederiva F, Guella G. Erratum: “Puckering free energy of pyranoses: An NMR and metadynamics–umbrella sampling investigation” [J. Chem. Phys. 133, 095104 (2010)]. J Chem Phys 2011. [DOI: 10.1063/1.3578611] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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43
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Sega M, Autieri E, Pederiva F. Pickett angles and Cremer–Pople coordinates as collective variables for the enhanced sampling of six-membered ring conformations. Mol Phys 2011. [DOI: 10.1080/00268976.2010.522208] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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44
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Hansen HS, Hünenberger PH. A reoptimized GROMOS force field for hexopyranose-based carbohydrates accounting for the relative free energies of ring conformers, anomers, epimers, hydroxymethyl rotamers, and glycosidic linkage conformers. J Comput Chem 2010; 32:998-1032. [PMID: 21387332 DOI: 10.1002/jcc.21675] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 08/12/2010] [Accepted: 08/17/2010] [Indexed: 11/07/2022]
Abstract
This article presents a reoptimization of the GROMOS 53A6 force field for hexopyranose-based carbohydrates (nearly equivalent to 45A4 for pure carbohydrate systems) into a new version 56A(CARBO) (nearly equivalent to 53A6 for non-carbohydrate systems). This reoptimization was found necessary to repair a number of shortcomings of the 53A6 (45A4) parameter set and to extend the scope of the force field to properties that had not been included previously into the parameterization procedure. The new 56A(CARBO) force field is characterized by: (i) the formulation of systematic build-up rules for the automatic generation of force-field topologies over a large class of compounds including (but not restricted to) unfunctionalized polyhexopyranoses with arbritrary connectivities; (ii) the systematic use of enhanced sampling methods for inclusion of experimental thermodynamic data concerning slow or unphysical processes into the parameterization procedure; and (iii) an extensive validation against available experimental data in solution and, to a limited extent, theoretical (quantum-mechanical) data in the gas phase. At present, the 56A(CARBO) force field is restricted to compounds of the elements C, O, and H presenting single bonds only, no oxygen functions other than alcohol, ether, hemiacetal, or acetal, and no cyclic segments other than six-membered rings (separated by at least one intermediate atom). After calibration, this force field is shown to reproduce well the relative free energies of ring conformers, anomers, epimers, hydroxymethyl rotamers, and glycosidic linkage conformers. As a result, the 56A(CARBO) force field should be suitable for: (i) the characterization of the dynamics of pyranose ring conformational transitions (in simulations on the microsecond timescale); (ii) the investigation of systems where alternative ring conformations become significantly populated; (iii) the investigation of anomerization or epimerization in terms of free-energy differences; and (iv) the design of simulation approaches accelerating the anomerization process along an unphysical pathway.
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Affiliation(s)
- Halvor S Hansen
- Laboratorium für Physikalische Chemie, ETH Zürich, CH-8093 Zürich, Switzerland
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