kCAT Inactivation of mushroom polyphenol oxidase

Avi Golan-Goldhirsh, John R. Whitaker

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Mushroom polyphenol oxidase is rapidly inactivated during turnover of substrate to product (kcat inactivation). As shown by use of [U-14C]-phenol as substrate, there is a marked nonspecific covalent binding of product to polyphenol oxidase (85 mol 14C-labeled product per mol of polyphenol oxidase subunits). In the presence of sufficient ascorbic acid to keep the product o-benzoquinone reduced to dihydroxyphenol, only 0.04 mol of 14C-labeled product per mol of polyphenol oxidase subunits was covalently bound. Therefore, kcat inactivation of mushroom polyphenol oxidase probably involves a free radical mechanism, rather than covalent binding of product at the active site proposed as one mechanism by Wood and Ingraham [5].

Original languageEnglish
Pages (from-to)141-147
Number of pages7
JournalJournal of Molecular Catalysis
Issue number2
StatePublished - 1 Sep 1985
Externally publishedYes

ASJC Scopus subject areas

  • General Engineering


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