Displacement of carbonates in Ca2UO2(CO3)3 by amidoxime-based ligands from free-energy simulations

2018 ◽  
Vol 47 (5) ◽  
pp. 1604-1613 ◽  
Author(s):  
Bo Li ◽  
Chad Priest ◽  
De-en Jiang
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Molecular Dynamics Simulations ◽  
Umbrella Sampling ◽  
Nacl Solution ◽  
Classical Molecular Dynamics ◽  
Energy Profiles ◽  
Energy Simulations ◽  
Dynamics Simulations ◽  
Free Energy Profiles

Classical molecular dynamics simulations coupled with umbrella sampling reveal the atomistic processes and free-energy profiles of the displacement of carbonate groups in the Ca2UO2(CO3)3 complex by amidoxime-based ligands in a 0.5 M NaCl solution.

scholarly journals Ring Puckering Landscapes of Glycosaminoglycan-Related Monosaccharides from Molecular Dynamics Simulations

2019 ◽  
Author(s):  
Irfan Alibay ◽  
Richard Bryce
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Molecular Dynamics Simulations ◽  
Biological Function ◽  
Enhanced Sampling ◽  
Energy Profiles ◽  
Ring Puckering ◽  
Dynamics Simulations ◽  
Ring Pucker ◽  
Free Energy Profiles

<p>The conformational flexibility of the glycosaminoglycans (GAGs) are 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 glucoronate and iduronate. These calculations indicate that in some cases, an excess of 15 microseconds are 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 eleven monosaccharides found in GAGs; this includes to our knowledge the first simulation study of sulfation effects on 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 GalNAc leads to reduced ring rigidity, with a significant lowering in energy of the <sup>1</sup>C<sub>4</sub> ring conformation; this observation may have implications for understanding the structural basis of the biological function of GalNAc-containing glycosaminoglycans such as dermatan sulfate.</p>

Adsorption of HF and HCl molecules on ice at 190 and 235 K from molecular dynamics simulations: Free energy profiles and residence times

2003 ◽  
Vol 118 (21) ◽  
pp. 9814-9823 ◽  
Author(s):  
C. Toubin ◽  
S. Picaud ◽  
P. N. M. Hoang ◽  
C. Girardet ◽  
R. M. Lynden-Bell ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Molecular Dynamics Simulations ◽  
Residence Times ◽  
Energy Profiles ◽  
Dynamics Simulations ◽  
Free Energy Profiles

scholarly journals Ring Puckering Landscapes of Glycosaminoglycan-Related Monosaccharides from Molecular Dynamics Simulations

2019 ◽  
Author(s):  
Irfan Alibay ◽  
Richard Bryce
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Molecular Dynamics Simulations ◽  
Biological Function ◽  
Enhanced Sampling ◽  
Energy Profiles ◽  
Ring Puckering ◽  
Dynamics Simulations ◽  
Ring Pucker ◽  
Free Energy Profiles

<p>The conformational flexibility of the glycosaminoglycans (GAGs) are 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 glucoronate and iduronate. These calculations indicate that in some cases, an excess of 15 microseconds are 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 eleven monosaccharides found in GAGs; this includes to our knowledge the first simulation study of sulfation effects on 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 GalNAc leads to reduced ring rigidity, with a significant lowering in energy of the <sup>1</sup>C<sub>4</sub> ring conformation; this observation may have implications for understanding the structural basis of the biological function of GalNAc-containing glycosaminoglycans such as dermatan sulfate.</p>

The molecular mechanism of ligand unbinding from the human telomeric G-quadruplex by steered molecular dynamics and umbrella sampling simulations

2015 ◽  
Vol 17 (19) ◽  
pp. 12857-12869 ◽  
Author(s):  
Jia-Kai Zhou ◽  
Dah-Yen Yang ◽  
Sheh-Yi Sheu
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Free Energy ◽  
Molecular Mechanism ◽  
Steered Molecular Dynamics ◽  
Umbrella Sampling ◽  
Energy Profiles ◽  
G Quadruplex ◽  
Free Energy Profiles

The mechanical properties and kinetic pathways of the ligand BMVC unbinding from the G-quadruplex were investigated via the computation of free energy profiles.

scholarly journals Combining free energy simulations and NMR chemical-shift perturbation to identify transient cation-π contacts in proteins

2019 ◽  
Author(s):  
André A. O. Reis ◽  
Raphael S. R. Sayegh ◽  
Sandro R. Marana ◽  
Guilherme M. Arantes
Keyword(s):  
Free Energy ◽  
Chemical Shift ◽  
Catalytic Domain ◽  
Chemical Shifts ◽  
Umbrella Sampling ◽  
Terminal Segment ◽  
Functional Roles ◽  
Energy Profiles ◽  
Energy Simulations ◽  
Dynamics Simulations

AbstractFlexible protein regions containing cationic and aromatic side-chains exposed to solvent may form transient cation-π interactions with structural and functional roles. To evaluate their stability and identify important intramolecular cation-π contacts, a combination of free energy profiles estimated from umbrella sampling with molecular dynamics simulations and chemical shift perturbations (CSP) obtained from NMR experiments is applied here to the complete catalytic domain of human phosphatase Cdc25B. This protein is a good model system for transient cation-π interactions as it contains only one Trp residue (W550) in the disordered C-terminal segment and a total of 17 Arg residues, many exposed to solvent. Eight putative Arg-Trp pairs were simulated here. Only R482 and R544 show bound profiles corresponding to important transient cation-π interactions, while the others have dissociative or almost flat profiles. These results are corroborated by CSP analysis of three Cdc25B point mutants (W550A, R482A and R544A) disrupting cation-π contacts. The proposed validation of statistically representative molecular simulations by NMR spectroscopy could be applied to identify transient contacts of proteins in general but carefully, as NMR chemical shifts are sensitive to changes in both molecular contacts and conformational distributions.

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