The effect of cupric ion on the reaction inactivation of ascorbic acid oxidase

Abstract

• 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. Other bivalent metal ions (Fe⁺⁺, Co⁺⁺, Ni⁺⁺, Zn⁺⁺) have been found to produce no significant retardation of the enzyme's action.

• 3. It has been demonstrated that the increased enzyme inactivation in the presence of Cu⁺⁺ cannot be attributed to the formation of H₂O₂ resulting from cupric ion catalysis of the aerobic oxidation of ascorbic acid.

• 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.