Network of Water Molecules Around Guanine Nucleotide in the Hras-GTP and -GDP Complexes by MD Simulations

GTP hydrolysis in Hras-GTP is suppressed in many human tumor cells, and this suppression is caused by structural change of Hras-GTP. We study the structures of Hras-GTP and -GDP complexes with water solvent by MD simulations. We investigate the distributions of the position and the orientation of water molecules around GTP/GDP in Hras-GTP/Hras-GDP. In this paper, it is found that the short time averaged values of orientation of water molecules near GTP are different from those near GDP. Our results suggest that the water molecules, which change the direction more often around GTP than around GDP in the short time, play important roles in GTP hydrolysis in Hras-GTP.