A statistical geometry analysis of simulated water-DMSO and water-MeCN binary mixtures for biomolecular studies

Multiway Analysis Reveals Hydrophobicity as the Sole Determinant of Dynamic Peptide-Acetonitrile-Water Association Behavior

Multiway analysis, a class of techniques developed for the purpose of studying multi-dimensional multivariate data, has been applied to study the dynamical structure of the first solvation layer of Ace-Gly-X-Gly-Nme peptides (where X is any amino acid) perturbed with the increase in concentrations of acetonitrile. Separate MD simulations of each peptide were carried out in five different concentrations of acetonitrile. Association of peptide, water, and acetonitrile atoms was quantified in terms of the relative abundance of Delaunay tetrahedra whose vertices could be centered on either the peptide, acetonitrile, or water atoms. A three-way data set comprising nine types of Delaunay tetrahedra in the first dimension, five concentrations of acetonitrile in the second dimension, and 26 different peptides in the third dimension was subjected to two different multiway methods viz., the constrained PARAFAC and the unconstrained Tucker3 analysis. The results unequivocally show that the dynamic peptide-acetonitrile-water association behavior could be solely explained by the hydrophobicity of the central amino acid. The study also demonstrates the utility of multiway analysis for the integration and interpretation of large number of separate MD simulations.

Conformational perturbation of peptides in presence of polar organic solvents

The critical role played by solvent environment in maintaining the conformational integrity of peptides and proteins is accepted without question. Numerous experiments have suggested that perturbing the solvent environment of peptides and proteins by the addition of polar organic solvents have important consequences for the conformation of these molecules. However, experimental studies of such perturbations often report different kinds of effects depending on the solvent used and/or the sequence/structure of the molecule under study. In this work we report a simulation based comparative study on the effects of adding two common organic solvents viz. Dimethyl sulfoxide (DMSO) and Acetonitrile (MeCN) on the dynamical conformation of a test peptide Ace-Gly-X-Gly-Nme where X is any amino acid. Our studies identify important differences in peptide solvation by these two solvents, which we attempt to correlate with the kinetic stability of the conformation, as well as the identity of the central 'X' residue in the test peptide.