Xanthine oxidase (XO) plays important roles in the tissue damge during ischemia-reperfusion by generating superoxide radicals, a reactive oxygen species. The present study examined effects of copper (II), a transition metal ion, on XO activity,
CuSO4 at
the concentration of 0.5μM inactivated 22% of XO. The inactivation was augmented by increasing concentration of copper (II, or incubation time. Among other tranistion metal ions tested, Hg(II) was most effective ; Others including Cu(I), Fe(II),
and
Fe(III) were not as effective as Cu(II), EDTA (50μM) almost completely abolished she inactivation of XO by 5μM copper (II). Protections by other copper chelator, such as sodium citrate and L-His were incomplete. The copper (II)-induced XO
inactivation
was not enhanced by the presence of hydrogen peroxide, and was not protected by various oxygen radical scavengers.
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