Title: The Oxidation of Phenylhydrazine by Tyrosinase
Authors: Sung, Yi-Ming
Gayam, Srivardhan Reddy
Wu, Shu-Pao
Department of Applied Chemistry
Keywords: Tyrosinase;Phenylhydrazine;Phenol;Superoxide
Issue Date: 1-Apr-2013
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 (25 A degrees C). The values of k (cat) 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 O-2 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.
URI: http://dx.doi.org/10.1007/s12010-013-0165-7
ISSN: 0273-2289
DOI: 10.1007/s12010-013-0165-7
Volume: 169
Issue: 8
Begin Page: 2420
End Page: 2429
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