Tetrahydrofolic Acid is a potent suicide substrate of mushroom tyrosinase.
The coenzyme tetrahydrofolic acid is the most rapid suicide substrate of tyrosinase that has been characterized to date. A kinetic study of the suicide inactivation process provides the kinetic constants that characterize it: λ(max), the maximum apparent inactivation constant; r, the partition ratio or the number of turnovers made by one enzyme molecule before inactivation; and k(cat) and K(m), the catalytic and Michaelis constants, respectively. From these values, it is possible to establish the ratio λ(max)/K(m), which represents the potency of the inactivation process. Besides acting as a suicide substrate of tyrosinase, tetrahydrofolic acid reduces o-quinones generated by the enzyme in its action on substrates, such as l-tyrosine and l-DOPA (o-dopaquinone), thus inhibiting enzymatic browning.
Grupo de Investigación de Enzimología (GENZ), Departamento de Bioquímica y Biología Molecular-A, Facultad de Biología, Universidad de Murcia , Espinardo, Murcia E-30100, Spain.
Francisco
F
García-Molina
Jose Luis
JL
Muñoz-Muñoz
Francisco
F
Martínez-Ortiz
Pedro Antonio
PA
García-Ruíz
Jose
J
Tudela
Francisco
F
García-Cánovas
Jose Neptuno
JN
Rodríguez-López
D000363:Agaricales / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007980:Levodopa / Q000037:antagonists & inhibitors; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D013379:Substrate Specificity; D013763:Tetrahydrofolates / Q000378:metabolism*; D014443:Tyrosine / Q000037:antagonists & inhibitors
D004791:Enzyme Inhibitors; D013763:Tetrahydrofolates; D014443:Tyrosine; C030371:5,6,7,8-tetrahydrofolic acid; D007980:Levodopa; D014442:Monophenol Monooxygenase