title: Effect of 3-hydroxyanthranilic acid on mushroom tyrosinase activity.
abstract: Tyrosinase is a copper containing protein which catalyzes the hydroxylation of monophenols and the oxidation of diphenols to o-quinones. The monophenolase activity of tyrosinase is characterized by a typical lag time. In this paper the influence of 3-hydroxyanthranilic acid on monophenolase activity of tyrosinase is reported. 3-Hydroxyanthranilic acid reduced the lag time of tyrosinase when the enzyme acted on N-acetyl-L-tyrosine and on 4-tert-butylphenol. In the presence of 3-hydroxyanthranilic acid, the reaction product 4-tert-butyl-o-benzoquinone, derived from 4-tert-butylphenol oxidation, was formed at a higher rate than in its absence. The results reported in this paper indicate that 3-hydroxyanthranilic acid could affect the enzymic activity of mushroom tyrosinase probably by acting as a diphenol substrate. A K(m) value of 0.78 mM was calculated for 3-hydroxyanthranilic acid as substrate. When tyrosinase acted on 4-tert-butylphenol, K(m) for 3-hydroxyanthranilic acid as a cofactor was estimated to be 37.5 microM. No effect was observed on the diphenolase activity of the enzyme acting on 4-tert-butylcatechol in the presence of 3-hydroxyanthranilic acid.
authors.affiliation: Istituto di Chimica Biologica, Università di Cagliari, Italy. rescigno@unica.it
authors.forename: A
authors.initials: A
authors.lastname: Rescigno
authors.forename: E
authors.initials: E
authors.lastname: Sanjust
authors.forename: G
authors.initials: G
authors.lastname: Soddu
authors.forename: A C
authors.initials: AC
authors.lastname: Rinaldi
authors.forename: F
authors.initials: F
authors.lastname: Sollai
authors.forename: N
authors.initials: N
authors.lastname: Curreli
authors.forename: A
authors.initials: A
authors.lastname: Rinaldi
mesh_terms: D015095:3-Hydroxyanthranilic Acid / Q000494:pharmacology*; D001487:Basidiomycota / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid; D016166:Free Radical Scavengers / Q000494:pharmacology*; D005656:Fungal Proteins / Q000187:drug effects / Q000378:metabolism*; D014442:Monophenol Monooxygenase / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D016166:Free Radical Scavengers; D005656:Fungal Proteins; D015095:3-Hydroxyanthranilic Acid; D014443:Tyrosine; C025787:N-acetyltyrosine; D014442:Monophenol Monooxygenase