title: Indirect inactivation of tyrosinase in its action on 4-tert-butylphenol.
abstract: Under anaerobic conditions, the o-diphenol 4-tert-butylcatechol (TBC) irreversibly inactivates met and deoxytyrosinase enzymatic forms of tyrosinase. However, the monophenol 4-tert-butylphenol (TBF) protects the enzyme from this inactivation. Under aerobic conditions, the enzyme suffers suicide inactivation when it acts on TBC. We suggest that TBF does not directly cause the suicide inactivation of the enzyme in the hydroxylase activity, but that the o-diphenol, which is necessary for the system to reach the steady state, is responsible for the process. Therefore, monophenols do not induce the suicide inactivation of tyrosinase in its hydroxylase activity, and there is a great difference between the monophenols that give rise to unstable o-quinones such as L-tyrosine, which rapidly accumulate L-dopa in the medium and those like TBF, after oxidation, give rise to a very stable o-quinone.
authors.affiliation: GENZ: Grupo de Investigación Enzimología, Departamento de Bioquímica y Biología Molecular-A, Facultad de Biología, Universidad de Murcia , Espinardo, Murcia , Spain .
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Muñoz-Muñoz
authors.forename: María del Mar
authors.initials: Mdel M
authors.lastname: García-Molina
authors.forename: Francisco
authors.initials: F
authors.lastname: García-Molina
authors.forename: Ramón
authors.initials: R
authors.lastname: Varon
authors.forename: Pedro Antonio
authors.initials: PA
authors.lastname: García-Ruiz
authors.forename: Jose Neptuno
authors.initials: JN
authors.lastname: Rodríguez-López
authors.forename: Francisco
authors.initials: F
authors.lastname: García-Cánovas
mesh_terms: D000363:Agaricales / Q000737:chemistry / Q000201:enzymology; D002396:Catechols / Q000737:chemistry*; D057075:Enzyme Assays; D004791:Enzyme Inhibitors / Q000737:chemistry*; D005656:Fungal Proteins / Q000737:chemistry* / Q000302:isolation & purification; D007700:Kinetics; D007980:Levodopa / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D012996:Solutions; D013379:Substrate Specificity; D014443:Tyrosine / Q000737:chemistry
chemical_list: D002396:Catechols; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D010636:Phenols; D012996:Solutions; C038096:tert-butylcatechol; D014443:Tyrosine; D007980:Levodopa; C006862:butylphen; D010100:Oxygen
keywords: Irreversible inhibition; TBC; TBF; suicide inactivation; tyrosinase