Sucrose in aqueous solution revisited, Part 2: adaptively biased molecular dynamics simulations and computational analysis of NMR relaxation.

ABSTRACT: We report 100 ns molecular dynamics simulations, at various temperatures, of sucrose in water (with concentrations of sucrose ranging from 0.02 to 4M), and in a 7:3 water-DMSO mixture. Convergence of the resulting conformational ensembles was checked using adaptive-biased simulations along the glycosidic ? and ? torsion angles. NMR relaxation parameters, including longitudinal (R?) and transverse (R?) relaxation rates, nuclear Overhauser enhancements (NOE), and generalized order parameter (S²) were computed from the resulting time-correlation functions. The amplitude and time scales of molecular motions change with temperature and concentration in ways that track closely with experimental results, and are consistent with a model in which sucrose conformational fluctuations are limited (with 80-90% of the conformations having ?-? values within 20° of an average conformation), but with some important differences in conformation between pure water and DMSO-water mixtures.

SUBMITTER: Xia J 

PROVIDER: S-EPMC3306822 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature