Abstract
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 language | English |
---|---|
Pages (from-to) | 122-127 |
Journal | IUBMB Life |
Volume | 66 |
Issue number | 2 |
Early online date | 27 Feb 2014 |
DOIs | |
Publication status | Published - Feb 2014 |
Keywords
- Agaricales/enzymology
- Catalysis
- Catechol Oxidase/metabolism
- Hydrogen-Ion Concentration
- Hydroquinones/metabolism
- Kinetics
- Monophenol Monooxygenase/chemistry
- Oxidation-Reduction
- Phenols