The oxidation of phenylhydrazine by tyrosinase

Yi Ming Sung, Srivardhan Reddy Gayam, Shu-Pao Wu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


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 (25°C). The values of kcat and K M for the oxidation of phenylhydrazine were obtained as 11.0 s -1 and 0.30 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, 1 mol O2 was required for the production of 1 mol phenol and 1/6 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.

Original languageEnglish
Pages (from-to)2420-2429
Number of pages10
JournalApplied Biochemistry and Biotechnology
Issue number8
StatePublished - 1 Apr 2013


  • Phenol
  • Phenylhydrazine
  • Superoxide
  • Tyrosinase

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