Altered redox affinity of xanthine oxidase active sites by copper(II) ions

Abstract

The interaction of Cu²⁺ ion with the redox centres of xanthine oxidase (XO) has been investigated using optical difference spectroscopic measurements. Anaerobic enzyme-reduction experiments using controlled and excess substrates (xanthine and NADH) have been performed to investigate the perturbation of XO active sites in the presence of Cu²⁺ ions. The results indicate an overall alteration in the redox affinities (i.e. affinity to accept electrons) of the active sites of XO by Cu²⁺ ion.