CARBAMYLATION INHIBITS THE FERROXIDASE ACTIVITY OF CERULOPLASMIN

The ferroxidase activity of caeruloplasmin (EC 1.16.3.1) is an importa nt antioxidant defence mechanism in man. In chronic renal failure prot eins become carbamylated as a result of reactions with urea-derived cy anate. We have therefore investigated the effects of carbamylation on the ferroxidase activity of caeruloplasmin. Increasing degrees of carb amylation produce a progressive impairment of ferroxidase activity mea sured using o-dianisidine as substrate, and the ability of caeruloplas min to load ferrous iron onto ovotransferrin is reduced. Carbamylation of caeruloplasmin may contribute to reduced antioxidant capacity in p atients with renal failure. (C) 1995 Academic Press, Inc.