THEORETICAL-STUDIES ON SPECIFIC INTERACTIONS BETWEEN BIOLOGICAL MOLECULES - INTERACTION OF CATIONIC ARGININE WITH ANIONIC GLUTAMIC-ACID

The ion-pair interaction energies between cationic arginine and anionic glutamic acid model molecules were calculated using the ab initio MO method with the 6-31G basis set and a correction of the basis set superposition errors (BSSE). The same systems were also investigated using the 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 with the ab initio MO method using the 6-31G basis set. The distance and angle dependencies of the ion-pair interactions are well represented by the ab initio potential. In contrast, they are not reproduced by the AMBER potential. The terms in the potential functions are analyzed and it is shown that the differences between both of the potential functions is caused by the short- and middle-range energy terms.