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Evidence against superoxide involvement in tyrosine hydroxylation by mushroom tyrosinase
Year:
1983
Source of publication :
Phytochemistry
Authors :
Kahn, Varda
;
.
Volume :
22
Co-Authors:
Kahn, V.
Golan-goldhirsh, A., Division of Food Technology, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
Whitaker, J.R., Division of Food Technology, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel, Department of Food Science and Technology, University of California, Davis, CA 95616, United States
Facilitators :
From page:
1875
To page:
1883
(
Total pages:
9
)
Abstract:
The possible involvement of superoxide anions in the hydroxylation of tyrosine by mushroom tyrosinase was studied. Superoxide dismutase and scavengers of superoxide ions of smaller MW than superoxide dismutase, such as nitroblue tetrazolium and copper salicylate, had no direct effect on the monohydroxyphenolase activity of mushroom tyrosinase. The kinetics of tyrosine hydroxylation, but not of DOPA oxidation, by mushroom tyrosinase was atrected by the addition of a xanthine-xanthine oxidase system. In the presence of the xanthine-xanthine oxidase system, the lag period of tyrosine hydroxylation was shortened compared to the lag period in the absence of the xanthine-xanthine oxidase system. The xanthine- xanthine oxidase system alone (without mushroom tyrosinase) had no effect on tyrosine conversion to dopachrome. Superoxide dismutase, catalase and hydroxyl radical scavengers counteracted to some extent the shortening of the lag period of tyrosine hydroxylation by mushroom tyrosinase caused by the xanthin e-xanthine oxidase system. It is suggested that the shortening of the lag period is due mainly to hydroxyl radicals generated by the xanthine-xanthine oxidase system via interaction of O2 -. and hydrogen paroxide (a Haber-Weiss type reaction). The data do not support the direct participation of superoxide anions in tyrosine hydroxylation by mushroom tyrosinase. © 1983.
Note:
Related Files :
DTPA, diethylenetriaminepenta-acetic acid.
SOD, superoxide dismutase
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More details
DOI :
10.1016/0031-9422(83)80005-3
Article number:
Affiliations:
Database:
Scopus
Publication Type:
article
;
.
Language:
English
Editors' remarks:
ID:
21790
Last updated date:
02/03/2022 17:27
Creation date:
16/04/2018 23:46
Scientific Publication
Evidence against superoxide involvement in tyrosine hydroxylation by mushroom tyrosinase
22
Kahn, V.
Golan-goldhirsh, A., Division of Food Technology, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
Whitaker, J.R., Division of Food Technology, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel, Department of Food Science and Technology, University of California, Davis, CA 95616, United States
Evidence against superoxide involvement in tyrosine hydroxylation by mushroom tyrosinase
The possible involvement of superoxide anions in the hydroxylation of tyrosine by mushroom tyrosinase was studied. Superoxide dismutase and scavengers of superoxide ions of smaller MW than superoxide dismutase, such as nitroblue tetrazolium and copper salicylate, had no direct effect on the monohydroxyphenolase activity of mushroom tyrosinase. The kinetics of tyrosine hydroxylation, but not of DOPA oxidation, by mushroom tyrosinase was atrected by the addition of a xanthine-xanthine oxidase system. In the presence of the xanthine-xanthine oxidase system, the lag period of tyrosine hydroxylation was shortened compared to the lag period in the absence of the xanthine-xanthine oxidase system. The xanthine- xanthine oxidase system alone (without mushroom tyrosinase) had no effect on tyrosine conversion to dopachrome. Superoxide dismutase, catalase and hydroxyl radical scavengers counteracted to some extent the shortening of the lag period of tyrosine hydroxylation by mushroom tyrosinase caused by the xanthin e-xanthine oxidase system. It is suggested that the shortening of the lag period is due mainly to hydroxyl radicals generated by the xanthine-xanthine oxidase system via interaction of O2 -. and hydrogen paroxide (a Haber-Weiss type reaction). The data do not support the direct participation of superoxide anions in tyrosine hydroxylation by mushroom tyrosinase. © 1983.
Scientific Publication
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