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 SA substrates, which give rise to a stable product as the oquinone 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 SB substrates, which include those whose o-quinone evolves with no clear stoichiometry (catechol, 4-methylcatechol, phenol and p-cresol) and, lastly, type SC substrates, which give rise to stable o-quinones (4-tert-butylcatechol/4-tert-butylphenol).
CITATION STYLE
Muñoz-Muñoz, J. L., Garcia-Molina, F., Varon, R., Tudela, J., Garcia-Cánovas, F., & Rodríguez-López, J. N. (2011). Kinetic cooperativity of tyrosinase. A general mechanism. Acta Biochimica Polonica, 58(3), 303–311. https://doi.org/10.18388/abp.2011_2240
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