title: 3-hydroxykynurenine as a substrate/activator for mushroom tyrosinase.
abstract: 3-Hydroxykynurenine is a tryptophan metabolite with an o-aminophenol structure. It is both a tyrosinase activator and a substrate, reducing the lag phase, stimulating the monophenolase activity, and being oxidized to xanthommatin. In the early stage of monophenol hydroxylation, catechol accumulation takes place, whereas 3-hydroxykynurenine is substantially unchanged and no significant amounts of the o-quinone are produced. These results suggest an activating action of 3-hydroxykynurenine toward o-hydroxylation of monophenols. 3-Hydroxykynurenine could therefore well act as a physiological device to control phenolics metabolism to catechols and quinonoids.
authors.affiliation: Dipartimento di Scienze Mediche Internistiche, Cattedra di Chimica Biologica, CSGI, Università di Cagliari, 09042, Monserrato (CA), Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Sanjust
authors.forename: Gloria
authors.initials: G
authors.lastname: Cecchini
authors.forename: Francesca
authors.initials: F
authors.lastname: Sollai
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Curreli
authors.forename: Antonio
authors.initials: A
authors.lastname: Rescigno
mesh_terms: D000364:Agaricus / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D007700:Kinetics; D007737:Kynurenine / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism; D010636:Phenols / Q000378:metabolism; D013053:Spectrophotometry; D013379:Substrate Specificity
chemical_list: D010636:Phenols; C005045:3-hydroxykynurenine; D007737:Kynurenine; D010088:Oxidoreductases; C412191:monophenolase; D014442:Monophenol Monooxygenase