IMPORTANCE OF EFFECTIVE CHARGES IN THE ANALYSIS OF ELECTRON-CONFORMATIONAL INTERACTIONS IN PEPTIDES

Dependences of electron distributions on conformations of model dipept ides and their water and glycerol complexes in ground electronic state s are studied by nb initio quantum chemistry methods. The influence of conformational distortions, hydrogen bonding, chemical group substitu tions, and electron attachment on the effective atomic charges for a n umber of dipeptides are analyzed. Various approaches to atomic charge determination are considered. It is shown, that the ESP method of char ge calculations is the most conformation-dependent approach and that o ptimization of the molecular geometry reduces charge variations consid erably.