W0222

A Database of Theoretical Aspherical Atom Electron Density Parameters for Electrostatic Analysis of Macromolecules. Xue Li, Anatoliy Volkov and Philip Coppens, Chemistry Dept., State Univ. of New York at Buffalo, Buffalo, NY 14260-3000.

A database of aspherical-atom multipole parameters has been built incorporating charge density parameters of a number of atom types. This database is comparable with that developed by Pichon-Pesme, Lecomte and Lachekar,¹ but is based on theoretical rather than experimental information. Values tabulated are the valence population P_val, the κ contraction/expansion coefficients and the multipole population parameters P_lm. They are obtained by refinement of valence-only structure factors with the Hansen-Coppens multipole formalism. Model structure factors are calculated from ab initio molecular electron densities at the B3LYP level obtained with the GAUSSIAN 98 program utilizing a 6-31G** basis set. More than 30 small organic molecules and peptide crystals are used to construct the database, which at this stage contains 32 different atom types, defined by element and specific bonding environment. The parameters are transferable to polypeptides and macromolecules. The ultimate aim is investigation of the nature of drug-substrate and protein-substrate interactions.

Support of this work by the National Institutes of Health (GM56829), the National Science Foundation (CHE9981864 and CHE0236317) is gratefully acknowledged.

¹Pichon-Pesme, V., Lecomte, C., and Lachekar, H., J. Phys. Chem., 1995, 99, 6242