Marcia C. Barbosa
Instituto de Física, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brasil
We performed molecular dynamics simulations to study the water structure and dynamics in the hydration shell of two biomolecules: the globular TS-Kappa protein and the DNA. Our results for the protein show that for a wide range of temperatures the diffusion coefficient of water near the protein surface is lower than in bulk. A crossover in the diffusion behavior of hydration water is observed at different temperatures at hydrophilic and hydrophobic vicinities of the protein. We found a correlation between the crossover in the hydrophilic case and the protein dynamical transition. We also study the mobility of water within the major and minor groove of the DNA. Similarly to what happens for the protein, the water shows a lower diffusion constant and a crossover associated with the DNA mobility. An explanation in terms of the competition between water-water water-protein H-bond formation is provided based on H-bond network analysis.