• Interaction energy—nitrogen lone electron pair of amines and a proton, angular dependency, drug-receptor systems;
  • Drug-receptor systems—interaction energy of the nitrogen lone electron pair of amines and a proton, angular dependency;
  • Amines—biologically active, interaction energy of the lone electron pair and a proton, angular dependency


Ab initio molecular orbital calculations with a 4-31G basis set have been performed to study the angular dependence of the interaction energy between a lone electron pair of nitrogen and a proton. In this study ammonia and trimethylamine were used as models of biologically active amines. A proton was used as a model of an electrophilic site at the receptor. Results obtained confirm previous indications that the energy required to bend the proton from the lone pair direction decreases markedly as the two species are further separated from one another. Implications regarding the interactions of drugs and hormones at specific receptors are discussed.