title: Mushroom tyrosinase has an ascorbate oxidase activity.
abstract: The reaction between mushroom tyrosinase and L-ascorbic acid was studied by oxymetric assays and evidence pointing to ascorbate oxidase activity of this enzyme has been obtained. The activity is clearly linear to enzyme concentration and the Michaelis constant for L-ascorbic acid has a value of 2.69 +/- 0.11 mM. Maximum activity is obtained at pH 7.5. A possible reaction mechanism, which is based on the different enzymatic forms of tyrosinase, is also presented.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universidad de Murcia, Spain.
authors.forename: J R
authors.initials: JR
authors.lastname: Ros
authors.forename: J N
authors.initials: JN
authors.lastname: Rodríguez-López
authors.forename: R
authors.initials: R
authors.lastname: Varón-Castellanos
authors.forename: F
authors.initials: F
authors.lastname: García-Canovas
mesh_terms: D001204:Ascorbate Oxidase / Q000378:metabolism*; D001205:Ascorbic Acid / Q000378:metabolism*; D001487:Basidiomycota / Q000201:enzymology*; D002712:Chlorides / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008543:Melanins / Q000096:biosynthesis; D015394:Molecular Structure; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D014334:Tropolone / Q000494:pharmacology
chemical_list: D002712:Chlorides; D008543:Melanins; D014334:Tropolone; D001204:Ascorbate Oxidase; D014442:Monophenol Monooxygenase; D001205:Ascorbic Acid; D010100:Oxygen