9418964 Doniach New computer simulation techniques for representing the conformational kinetics of polypeptides and proteins in solution will be developed. These techniques will comprise two developments: the use of overdamped constrained Langevin dynamics to represent the kinetics of a polypeptide chain, in which the positions in Cartesian space and forces on all atoms of the peptide are taken into account; and the development of the representation of the interaction of the peptide with solvent. The overdamped constrained Langevin dynamics, which has recently been published by Gronbech-Jensen and Doniach, is obtained by projecting out all components of the force field which would tend to alter constrained bond lengths, and hence, bond angles in the peptide backbone and side chains. The treatment of solvent will be based both on a Langevin dynamics approach to explicit water molecules, their interactions between each other and with the peptide, and on a novel "mean-field" approach to the calculation of the hydration shell of a polypeptide out to a distance of 8 Angstrom from the surface atoms. These new techniques will be applied to the simulation of the helix-random coil transitions in small polypeptide chains 13 to 20 residues which are known to have nascent helix properties. ***
