Kcat inactivation of mushroom polyphenol oxidase Academic Article uri icon

abstract

  • Mushroom polyphenol oxidase is rapidly inactivated during turnover of substrate to product (k cat inactivation). As shown by use of [U-14 C]-phenol as substrate, there is a marked nonspecific covalent binding of product to polyphenol oxidase (85 mol 14 C-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 14 C-labeled product per mol of polyphenol oxidase subunits was covalently bound. Therefore, k cat 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].

publication date

  • September 1, 1985