title: Kinetic cooperativity of tyrosinase. A general mechanism.
abstract: Tyrosinase shows kinetic cooperativity in its action on o-diphenols, but not when it acts on monophenols, confirming that the slow step is the hydroxylation of monophenols to o-diphenols. This model can be generalised to a wide range of substrates; for example, type S(A) substrates, which give rise to a stable product as the o-quinone evolves by means of a first or pseudo first order reaction (α-methyl dopa, dopa methyl ester, dopamine, 3,4-dihydroxyphenylpropionic acid, 3,4-dihydroxyphenylacetic acid, α-methyl-tyrosine, tyrosine methyl ester, tyramine, 4-hydroxyphenylpropionic acid and 4-hydroxyphenylacetic acid), type S(B) substrates, which include those whose o-quinone evolves with no clear stoichiometry (catechol, 4-methylcatechol, phenol and p-cresol) and, lastly, type S(C) substrates, which give rise to stable o-quinones (4-tert-butylcatechol/4-tert-butylphenol).
authors: GENZ: Grupo de Investigación Enzimología, Departamento de Bioquímica y Biología Molecular-A, Facultad de Biología, Universidad de Murcia, Espinardo, Murcia, Spain.
authors: Jose Luis
authors: JL
authors: Muñoz-Muñoz
authors: Francisco
authors: F
authors: Garcia-Molina
authors: Ramón
authors: R
authors: Varon
authors: Jose
authors: J
authors: Tudela
authors: Francisco
authors: F
authors: Garcia-Cánovas
authors: Jose N
authors: JN
authors: Rodríguez-López
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000737:chemistry / Q000378:metabolism; D002109:Caffeic Acids / Q000737:chemistry / Q000378:metabolism; D002396:Catechols / Q000737:chemistry / Q000378:metabolism; D003408:Cresols / Q000737:chemistry / Q000378:metabolism; D003846:Deoxyepinephrine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D004298:Dopamine / Q000737:chemistry / Q000378:metabolism; D008956:Models, Chemical; D014442:Monophenol Monooxygenase / Q000737:chemistry* / Q000378:metabolism*; D010636:Phenols / Q000737:chemistry / Q000378:metabolism; D010648:Phenylacetates / Q000737:chemistry / Q000378:metabolism; D010666:Phenylpropionates / Q000737:chemistry / Q000378:metabolism; D011809:Quinones / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D002109:Caffeic Acids; D002396:Catechols; D003408:Cresols; D010636:Phenols; D010648:Phenylacetates; D010666:Phenylpropionates; D011809:Quinones; D015102:3,4-Dihydroxyphenylacetic Acid; C000995:3,4-dihydroxyphenylpropionic acid; C018599:4-methylcatechol; C032538:4-cresol; C008070:4-hydroxyphenylacetic acid; C023492:alpha-methyldopamine; C008869:phloretic acid; D014442:Monophenol Monooxygenase; C034221:catechol; D003846:Deoxyepinephrine; D004298:Dopamine