RESUMO
Proteins are known to be carbamylated as a result of reactions with ureaderived cyanate. We investigated the effect of carbamylation by cyanate on the catalase activity which is known that its decreased activity contributes to cataract formation, and on the lens protein. Catalase and lens protein were carbamylated by incubation with cyanate at 37degrees C. The extent of carbamylation was monitored by following the loss of free amino group using trinitrobenzenesulphonic acid. The level of carbamylated protein was 76% in patients with cataract. Carbamylated proteins in normal lens from rabbits and carbamylated catalase were increased as the time of exposure to cyanate activity. Our results suggest that cyanate is an inhibitor of catalase, and carbamylation of catalase as a result of reaction with ureaderived cyanate may contribute to cataract formation.