AEROBIC OXIDATION OF TRIOSE REDUCTONE BY CRYSTALLINE TURNIP PEROXIDASE

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Abstract
The oxidation of triose reductone (RnH2) by recrystallized turnip peroxidase proceeds at pH 4.6 in 2 successive stages as follows: RnH2 + O2[forward arrow] Rn + H2O2; RnH2 + H2O2[forward arrow] Rn + 2 H2O. The enzyme acts as oxidase in the first reaction and as peroxidase in the second reaction. The over-all reaction is enhanced by a trace of H2O2 and is inhibited by addition of catalase. Autoxidative formation of H2O2 is confirmed by spectro-photometry at 240 mu, but with a reaction rate using a larger amt. of enzyme, the accumulation of H2O2 in the initial stage is lowered. 10-5 [image] Mn++, Co++, 8x10-8 [image] Cu++ and a trace of Hg++ accelerate RnH2 oxidation by the enzyme at pH 7-8. Only Mn++ is effective at pH 4-6, and 10-5 [image] Cu++ and Fe++ are rather inhibitory.