title: 5-S-cysteinyldopa as a substrate for tyrosinase.
abstract: Oxidation of 5-S-cysteinyldopa by mushroom tyrosinase was studied by measuring 5-S-cysteinyldopa consumption with HPLC. 5-S-cysteinyldopa was found to be a substrate for tyrosinase, but our results suggests that a self-catalysed oxidation induced by enzymatically formed 5-S-cysteinyl dopaquinone also takes place. Dopa oxidation by tyrosinase was determined by measuring substrate consumption with HPLC. The oxidation of 5-S-cysteinyldopa was markedly accelerated in the presence of dopa. This could be explained by dopaquinone oxidation of 5-S-cysteinyldopa, which has a lower oxidation potential than dopa.
mesh_terms: D004156:Catechol Oxidase; D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D003548:Cysteinyldopa; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives; D008543:Melanins / Q000378:metabolism; D014442:Monophenol Monooxygenase
chemical_list: D008543:Melanins; D003548:Cysteinyldopa; D004295:Dihydroxyphenylalanine; D004156:Catechol Oxidase; D014442:Monophenol Monooxygenase