Hydrophobic and electrostatic interactions in ionic micelles. Problems in calculating monomer contributions to the free energy

1969 ◽  
Vol 73 (6) ◽  
pp. 2054-2056 ◽  
Author(s):  
Pasupati Mukerjee
Keyword(s):  
Free Energy ◽  
Electrostatic Interactions ◽  
Ionic Micelles

scholarly journals Prediction of GluN2B-CT1290-1310/DAPK1 Interaction by Protein–Peptide Docking and Molecular Dynamics Simulation

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 3018 ◽  
Author(s):  
Gao Tu ◽  
Tingting Fu ◽  
Fengyuan Yang ◽  
Lixia Yao ◽  
Weiwei Xue ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Electrostatic Interactions ◽  
Binding Free Energy ◽  
Computational Simulation ◽  
Critical Role ◽  
Dynamics Simulation ◽  
Peptide Docking ◽  
C Terminus ◽  
Free Energy Decomposition

The interaction of death-associated protein kinase 1 (DAPK1) with the 2B subunit (GluN2B) C-terminus of N-methyl-D-aspartate receptor (NMDAR) plays a critical role in the pathophysiology of depression and is considered a potential target for the structure-based discovery of new antidepressants. However, the 3D structures of C-terminus residues 1290–1310 of GluN2B (GluN2B-CT1290-1310) remain elusive and the interaction between GluN2B-CT1290-1310 and DAPK1 is unknown. In this study, the mechanism of interaction between DAPK1 and GluN2B-CT1290-1310 was predicted by computational simulation methods including protein–peptide docking and molecular dynamics (MD) simulation. Based on the equilibrated MD trajectory, the total binding free energy between GluN2B-CT1290-1310 and DAPK1 was computed by the mechanics generalized born surface area (MM/GBSA) approach. The simulation results showed that hydrophobic, van der Waals, and electrostatic interactions are responsible for the binding of GluN2B-CT1290–1310/DAPK1. Moreover, through per-residue free energy decomposition and in silico alanine scanning analysis, hotspot residues between GluN2B-CT1290-1310 and DAPK1 interface were identified. In conclusion, this work predicted the binding mode and quantitatively characterized the protein–peptide interface, which will aid in the discovery of novel drugs targeting the GluN2B-CT1290-1310 and DAPK1 interface.

Ice Ih–Water Interfacial Free Energy of Simple Water Models with Full Electrostatic Interactions

2012 ◽  
Vol 8 (7) ◽  
pp. 2383-2390 ◽  
Author(s):  
Ruslan L. Davidchack ◽  
Richard Handel ◽  
Jamshed Anwar ◽  
Andrey V. Brukhno
Keyword(s):  
Free Energy ◽  
Electrostatic Interactions ◽  
Interfacial Free Energy ◽  
Water Models

scholarly journals Optimization of Protein-Ligand Electrostatic Interactions Using an Alchemical Free-Energy Method

2019 ◽  
Author(s):  
Alexander Wade ◽  
David Huggins
Keyword(s):  
Free Energy ◽  
Binding Affinity ◽  
Energy Method ◽  
Electrostatic Interactions ◽  
Protein Complexes ◽  
Chemical Changes ◽  
Average Improvement ◽  
Explicit Solvent ◽  
Energy Perturbation ◽  
Alchemical Free Energy

<p>We present an alchemical free-energy method for optimizing the partial charges of a ligand to maximize the binding affinity with a receptor. This methodology can be applied to known ligand-protein complexes to determine an optimized set of ligand partial atomic changes. Three protein-ligand complexes have been optimized in this work: FXa, P38 and androgen receptor. The optimization of the ligand charges yielded improvements to binding affinity for all three systems. The sets of optimized charges can be used to identify design principles for chemical changes to the ligand which improve the binding affinity. In this work, beneficial chemical mutations are generated from these principles and the resulting molecules tested using free-energy perturbation calculations. We show that three quarters of our chemical changes are predicted to improve the binding affinity, with an average improvement of approximately 1 kcal/mol. The results demonstrate that charge optimization in explicit solvent is a useful tool for predicting beneficial chemical changes such as pyridinations, fluorinations, and oxygen to sulphur mutations. </p>

scholarly journals Omicron SARS-CoV-2 Variant Spike Protein Shows an Increased Affinity to the Human ACE2 Receptor: An In Silico Analysis

Pathogens ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 45
Author(s):  
Joseph Thomas Ortega ◽  
Beata Jastrzebska ◽  
Hector Rafael Rangel
Keyword(s):  
Free Energy ◽  
Electrostatic Interactions ◽  
Structural Model ◽  
Binding Free Energy ◽  
In Silico Analysis ◽  
Spike Protein ◽  
Medical Community ◽  
Converting Enzyme ◽  
Angiotensin Converting Enzyme 2 ◽  
Silico Analysis

The rise of SARS-CoV-2 variants, with changes that could be related to an increased virus pathogenicity, have received the interest of the scientific and medical community. In this study, we evaluated the changes that occurred in the viral spike of the SARS-CoV-2 Omicron variant and whether these changes modulate the interactions with the angiotensin-converting enzyme 2 (ACE2) host receptor. The mutations associated with the Omicron variant were retrieved from the GISAID and covariants.org databases, and a structural model was built using the SWISS-Model server. The interaction between the spike and the human ACE2 was evaluated using two different docking software, Zdock and Haddock. We found that the binding free energy was lower for the Omicron variant as compared to the WT spike. In addition, the Omicron spike protein showed an increased number of electrostatic interactions with ACE2 than the WT spike, especially the interactions related to charged residues. This study contributes to a better understanding of the changes in the interaction between the Omicron spike and the human host ACE2 receptor.

scholarly journals Rationalizing generation of broad spectrum antibiotics with the addition of a primary amine

2021 ◽  
Author(s):  
Nandan Haloi ◽  
Archit Kumar Vasan ◽  
Emily Jane Geddes ◽  
Arjun Prasanna ◽  
Po-Chao Wen ◽  
...  
Keyword(s):  
Free Energy ◽  
Primary Amine ◽  
Electrostatic Interactions ◽  
Degrees Of Freedom ◽  
Md Simulations ◽  
Free Energy Calculations ◽  
Gram Negative ◽  
Molecular Conformations ◽  
Energy Calculations ◽  
Cell Accumulation

Antibiotic resistance of Gram-negative bacteria is largely attributed to the low permeability of their outer membrane (OM). Recently, we disclosed the eNTRy rules, a key lesson of which is that the introduction of a primary amine enhances OM permeation in certain contexts. To understand the molecular basis for this finding, we perform an extensive set of molecular dynamics (MD) simulations and free energy calculations comparing the permeation of aminated and amine-free antibiotic derivatives through the most abundant OM porin of E. coli, OmpF. To improve sampling of conformationally flexible drugs in MD simulations, we developed a novel, Monte Carlo and graph theory based algorithm to probe more efficiently the rotational and translational degrees of freedom visited during the permeation of the antibiotic molecule through OmpF. The resulting pathways were then used for free-energy calculations, revealing a lower barrier against the permeation of the aminated compound, substantiating its greater OM permeability. Further analysis revealed that the amine facilitates permeation by enabling the antibiotic to align its dipole to the luminal electric field of the porin and while forming favorable electrostatic interactions with specific, highly-conserved charged residues. The importance of these interactions in permeation was further validated with experimental mutagenesis and whole cell accumulation assays. Overall, this study provides insights on the importance of the primary amine for antibiotic permeation into Gram-negative pathogens that could help the design of future antibiotics. We also offer a new computational approach for calculating free-energy of processes where relevant molecular conformations cannot be efficiently captured.

scholarly journals Electrostatic Interactions with Choline and Phosphate Groups Regulate Cisplatin Permeation through a Dioleoylphosphocholine Bilayer

2020 ◽  
Author(s):  
Lorena Ruano ◽  
Gustavo Cárdenas ◽  
Juan Jose Nogueira
Keyword(s):  
Free Energy ◽  
Lipid Bilayers ◽  
Long Range ◽  
Electrostatic Interactions ◽  
Umbrella Sampling ◽  
Energy Minimum ◽  
Free Energy Minimum ◽  
Dynamics Simulations ◽  
First Moment ◽  
Phosphate Groups

The investigation of the intermolecular interactions between platinum-based anticancer drugs and lipid bilayers is of special relevance to unveil the mechanisms involved in different steps of the mode of action of these drugs. We have simulated the permeation of cisplatin through a model membrane composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine lipids by means of umbrella sampling classical molecular dynamics simulations. The initial physisorption of cisplatin in the polar region of the membrane is controlled, in a first moment, by long-range electrostatic interactions with the choline groups, which trap the drug in a shallow free-energy minimum. Then, cisplatin is driven to a deeper free-energy minimum by long-range electrostatic interactions with the phosphate groups. From this minimum to the middle of the bilayer the electrostatic repulsion between cisplatin and the choline groups partially cancels out the electrostatic attraction between cisplatin and the phosphate groups, inducing a general drop of the total interaction with the polar heads. In addition, the attractive interactions with the non-polar tails, which are dominated by van der Waals contributions, gain significance. The large energy barrier found when going from the global minimum to the middle of the membrane indicates that the non-electrostatic interactions between the drug and the non-polar tails are badly reproduced by the fixed point-charge force field used here, and that the introduction of polarization effects are likely necessary.

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