Catalysis and inactivation of tyrosinase in its action on hydroxyhydroquinone

Maria del Mar Garcia-Molina, Jose Luis Muñoz-Muñoz, Jose Berna, Pedro Antonio García-Ruiz, Jose Neptuno Rodriguez-Lopez, Francisco Garcia-Canovas

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6 Citations (Scopus)


Hydroxyhydroquinone (HHQ) was characterized kinetically as a tyrosinase substrate. A kinetic mechanism is proposed, in which HHQ is considered as a monophenol or as an o-diphenol, depending on the part of the molecule that interacts with the enzyme. The kinetic parameters obtained from an analysis of the measurements of the initial steady state rate of 2-hydroxy p-benzoquinone formation were kcatapp=229.0±7.7 s(-1) and KMapp,HHQ=0.40±0.05 mM. Furthermore, the action of tyrosinase on HHQ led to the enzyme's inactivation through a suicide inactivation mechanism. This suicide inactivation process was characterized kinetically by λmaxapp (the apparent maximum inactivation constant) and r, the number of turnovers made by 1 mol of enzyme before being inactivated. The values of λmaxapp and r were (8.2±0.1)×10(-3) s(-1) and 35,740±2,548, respectively.

Original languageEnglish
Pages (from-to)122-127
JournalIUBMB Life
Issue number2
Early online date27 Feb 2014
Publication statusPublished - Feb 2014


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