TY - JOUR
T1 - Catalysis and inactivation of tyrosinase in its action on hydroxyhydroquinone
AU - del Mar Garcia-Molina, Maria
AU - Muñoz-Muñoz, Jose Luis
AU - Berna, Jose
AU - García-Ruiz, Pedro Antonio
AU - Rodriguez-Lopez, Jose Neptuno
AU - Garcia-Canovas, Francisco
N1 - © 2014 International Union of Biochemistry and Molecular Biology.
PY - 2014/2
Y1 - 2014/2
N2 - 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.
AB - 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.
KW - Agaricales/enzymology
KW - Catalysis
KW - Catechol Oxidase/metabolism
KW - Hydrogen-Ion Concentration
KW - Hydroquinones/metabolism
KW - Kinetics
KW - Monophenol Monooxygenase/chemistry
KW - Oxidation-Reduction
KW - Phenols
UR - https://www.scopus.com/pages/publications/84896391650
U2 - 10.1002/iub.1250
DO - 10.1002/iub.1250
M3 - Article
C2 - 24578277
SN - 1521-6543
VL - 66
SP - 122
EP - 127
JO - IUBMB Life
JF - IUBMB Life
IS - 2
ER -
