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Abstract
Tyrosinase was found to catalyze the oxidation of phenylhydrazine to phenol in a reaction that did not resemble those typically performed by tyrosinase. The kinetics of this reaction was investigated by measuring the initial velocity of the formation of phenol (25Â °C). The values of k ^sub cat^ and K ^sub M^ for the oxidation of phenylhydrazine were obtained as 11.0Â s^sup â '1^ and 0.30Â mM, respectively. The generation of superoxides during The Oxidation of Phenylhydrazine by Tyrosinase was monitored by nitroblue tetrazolium (NBT) assay. In the phenylhydrazine-tyrosinase reaction, 1Â mol O2 was required for the production of 1Â mol phenol and 1/6Â mol superoxide. The decomposition of superoxide by superoxide dismutase enhanced the rate constant of the oxidation of phenylhydrazine. Phenol formed in The Oxidation of Phenylhydrazine by Tyrosinase was further oxidized by tyrosinase to an o-quinone, after The Oxidation of Phenylhydrazine by Tyrosinase was almost completed.[PUBLICATION ABSTRACT]