TY - JOUR
T1 - kCAT Inactivation of mushroom polyphenol oxidase
AU - Golan-Goldhirsh, Avi
AU - Whitaker, John R.
N1 - Funding Information:
This work was supported by BARD Project No. f-223-80. We thank Virginia DuBowy for typing the m~usc~pt and checking the references.
PY - 1985/9/1
Y1 - 1985/9/1
N2 - 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].
AB - 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].
UR - http://www.scopus.com/inward/record.url?scp=0022130941&partnerID=8YFLogxK
U2 - 10.1016/0304-5102(85)80001-8
DO - 10.1016/0304-5102(85)80001-8
M3 - Article
AN - SCOPUS:0022130941
SN - 0304-5102
VL - 32
SP - 141
EP - 147
JO - Journal of Molecular Catalysis
JF - Journal of Molecular Catalysis
IS - 2
ER -