A STATISTICAL-MECHANICAL DESCRIPTION OF BIOMOLECULAR HYDRATION

An efficient and accurate theoretical description of the structural hy dration of biological macromolecules is presented. The hydration of mo lecules of almost arbitrary size (tRNA, antibody-antigen complexes, ph otosynthetic reaction centre) can be studied in solution and in the cr ystalline environment. The biomolecular structure obtained from X-ray crystallography, NMR or modelling is required as input information. Th e structural arrangement of water molecules near a biomolecular surfac e is represented by the local water density, analogous to the correspo nding electron density in an X-ray diffraction experiment. The water-d ensity distribution is approximated in terms of two- and three-particl e correlation functions of solute atoms with water using a potentials- of-mean-force expansion.