The effect of cupric ion on the reaction inactivation of ascorbic acid oxidase.
Abstract 1. 1. The reaction inactivation of functioning ascorbic acid oxidase has been found to be greatly increased in the presence of free cupric ion, whereas the incubation of nonfunctioning enzyme with Cu ++ results in no apparent inactivation. 2. 2. Other bivalent metal ions (Fe ++ , Co ++ , Ni ++ , Zn ++ ) have been found to produce no significant retardation of the enzyme's action. 3. 3. It has been demonstrated that the increased enzyme inactivation in the presence of Cu ++ cannot be attributed to the formation of H 2 O 2 resulting from cupric ion catalysis of the aerobic oxidation of ascorbic acid. 4. 4. The significance of the Cu ++ effect in respect to the possible role of —SH group participation in the enzyme's function is briefly discussed.