THEORETICAL-STUDIES ON HYDROGEN-BONDING INTERACTIONS BETWEEN PEPTIDE UNITS

The hydrogen bonding interaction energies between peptide units were calculated using the ab initio MO method with the STO-3G, 7,3/2,1 and 6-31G basis sets and a correction of the basis set superposition errors (BSSE). The same systems were also investigated using an ab initio potential which has recently been developed and the AMBER potential, which is widely used. The energy profiles calculated using the ab initio potential are similar to those calculated using the 6-31G basis set. The distance and angle dependencies of the hydrogen bonding interactions are well represented by the ab initio potential. In contrast, they are not reproduced by the AMBER potential.