A conformational analysis of histamine, and its protonated or deprotonated forms: an ab initio study

Histamine, a neurotransmitter contains an imidazole ring which may be protonated or deprotonated. The present study was dedicated to the two tautomeric and their protonated and deprotonated forms. Throughout the whole study, the side chain nitrogen was kept in its protonated form. Potential energy surface scanning and reaction path calculation between two optimized conformations were carried out using restricted Hartree-Fock method with 3-21G basis set (RHF/3-21G). (C) 2004 Published by Elsevier B.V.