title: Suicide inactivation of tyrosinase in its action on tetrahydropterines.
abstract: Tetrahydrobiopterin (BH(4)), methyl-tetrahydropterin (MBH(4)) and dimethyl-tetrahydropterin (DMBH(4)) are oxidized by tyrosinase in a process during which the suicide inactivation of tyrosinase may occur. From the kinetic study of this process, [Formula: see text] (apparent maximum constant for the suicide inactivation), [Formula: see text] (Michaelis constant for the substrate) and r (number of turnovers that the enzyme makes before the inactivation) can be obtained. From the results obtained, it can be deduced that the velocity of the inactivation governed by ([Formula: see text]) and the potency of the same ([Formula: see text]) follow the order: BH(4) > MBH(4) > DMBH(4).
authors.affiliation: Grupo de Investigación Enzimología, Departamento de Bioquímica y Biología Molecular-A, Facultad de Biología, Universidad de Murcia, E-30100, Espinardo, Murcia, Spain.
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Muñoz-Muñoz
authors.forename: Francisco
authors.initials: F
authors.lastname: Garcia-Molina
authors.forename: Enrique
authors.initials: E
authors.lastname: Arribas
authors.forename: Pedro Antonio
authors.initials: PA
authors.lastname: Garcia-Ruíz
authors.forename: Jose
authors.initials: J
authors.lastname: Tudela
authors.forename: Francisco
authors.initials: F
authors.lastname: Garcia-Cánovas
authors.forename: Jose Neptuno
authors.initials: JN
authors.lastname: Rodríguez-López
mesh_terms: D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D007700:Kinetics; D015394:Molecular Structure; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000378:metabolism; D011622:Pterins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D011622:Pterins; C011552:tetrahydropterin; D014442:Monophenol Monooxygenase