The effect of N-methylation on the thermodynamic and spectroscopic features of a peptide mimicking the active site of NiSOD enzyme

Abstract

In this thesis work, the thermodynamic and spectroscopic features together with SOD activity studies of N-methylated peptide mimicking the active site of NiSOD enzyme were studied. To gain insights into mechanism of NiSOD-assisted superoxide dismutation, particularly the role of N-terminal amine protons from histidine in stabilizing superoxide anion via H-bond formation, the terminal amino group was substituted with a methyl group. The results were compared with those observed for the wild-type fragment of NiSOD. This study demonstrates that although the N-methylated peptide mimicking the active site of NiSOD exhibits structural features similar to wt-NiSOD, it fails to retain catalytic activity, clearly suggesting that the terminal amino group is involved in the hydrogen-bond network surrounding the catalytic center.