Formation of carnosine - an ab initio study

Roman Boča,Beata Vranovičová

doi:10.36547/nbc.1010

Abstract

Formation of carnosine from histidine and b-alanine is studied by ab initio MO-LCAO-SCF method followed by the perturbative configuration interaction (MP2) in vacuo. After the full geometry optimization at the SCF level, the molecular properties were evaluated and followed by the vibrational-rotational analysis. Consequently, the energy, entropy and free energy were evaluated for the reactants and products of the reaction histidine + beta-alanine = carnosine + H2O and finally the equilibrium constant was enumerated.

Highlights

Carnosine is a substance with multi-beneficial effects (Boldyrev et al 2013)
As carnosine penetrates the blood-brain barrier (BBB) and causes only little side effects, it possesses high utility potential. It serves as a reservoir of histidine which is transformed to histamine by L-histidinedecarboxylase; the histamine itself does not penetrate BBB
X-ray structure data for the reactants and products of the reaction (Eq 1) have been retrieved from the CCDC database (Cambridge Crystallographic Data Centre). These solid-state structures were used as an initial guess for the full geometry optimization in vacuo

Summary

Introduction

The above results have been compared with those obtained by the enlarged basis set 6-311G(d,p) after the full geometry optimization at the MP2 level. The MO-LCAO-SCF calculations started from the experimental solid-state geometry that is a zwitterionic form for histidine, -alanine and carnosine. The full geometry optimization converged to the zwitterionic form (hereafter Z) as displayed in Fig. 2 for histidine. Start from the reallocated geometry (zwitterion), final hydrogen atom zwitterionic form with the NH...O contact

Results

Conclusion