A CONNECTED CLUSTER OF HYDRATION AROUND MYOGLOBIN - CORRELATION BETWEEN MOLECULAR-DYNAMICS SIMULATIONS AND EXPERIMENT

An analysis of a molecular dynamics simulation of metmyoglobin in an e xplicit solvent environment of 3,128 water molecules has been performe d. Both statics and dynamics of the protein-solvent interface are addr essed in a comparison with experiment. Three-dimensional density distr ibutions, temperature factors, and occupancy weights are computed for the solvent by using the trajectory coordinates. Analysis of the hydra tion leads to the localization of more than 500 hydration sites distri buted into multiple layers of solvation located between 2.6 and 6.8 An gstrom from the atomic protein surface. After locating the local solve nt density maxima or hydration sites we conclude that water molecules of hydration positions and hydration sites are distinct concepts. Both global and detailed properties of the hydration cluster around myoglo bin are compared with recent neutron and X-ray data on myoglobin. Ques tions arising from differences between X-ray and neutron data concerni ng the locations of the protein-bound water are investigated. Analysis of water site differences found from X-ray and neutron experiments co mpared with our simulation shows that the simulation gives a way to un ify the hydration picture given by the two experiments. (C) 1994 Wiley -Liss, Inc.