Thermo-Kinetic Investigation of Comparative Ligand Effect on Cysteine Iron Redox Reaction

Abstract

Transition metal ions in their free state bring unwanted biological oxidations generating oxidative stress. The ligand modulated redox potential can be indispensable in prevention of such oxidative stress by blocking the redundant bio-redox reactions. In this study we investigated the comparative ligand effect on the thermo-kinetic aspects of biologically important cysteine iron (III) redox reaction using spectrophotometric and potentiometric methods. The results were corroborated with the complexation effect on redox potential of iron(III)-iron(II) redox couple. The selected ligands were found to increase the rate of cysteine iron (III) redox reaction in proportion to their stability of iron (II) complex (EDTA < terpy < bipy < phen). A kinetic profile and the catalytic role of copper (II) ions by means of redox shuttle mechanism for the cysteine iron (III) redox reaction in presence of 1,10-phenanthroline (phen) ligand is also reported.