Abstract

A MINI REVIEW ON COMPUTATIONAL STUDY OF TAUTOMERISM IN BETA- LACTAM ANTIBIOTICS BY AUSTIN MODEL-1(AM1) METHOD

Dr. Bojja Rajeshwar Rao*

Abstract

The geometry, conformation, electronic structure of beta-lactam antibiotics i.e. benzylpenicillin, methicillin, phenethicillin, cephapirin and their tautomers have been optimized and calculated in the gas phase by semi-empirical molecular orbital AM1 method usually considering an isolated molecule, which is surrounded by vacuum. The mechanism of tautomerism in beta-lactam antibiotics have been studied by comparison of the different positions of net charges at hetero- atoms in the molecule. Further, the heats of formation (ΔHf o), dipole moment (μ), ionization potential (IP), full atomic charges and energies of frontier molecular orbitals (EHOMO and ELUMO) have been performed and their stable conformations have also been evaluated.

Keywords: AM1, lactam, lactim, enol, tautomerism, benzylpenicillin, methicillin, phenethicillin, cephapirin, induction effect.