Oxygen Michaelis constants for tyrosinase.
The Michaelis constant of tyrosinase for oxygen in the presence of monophenols and o-diphenols, which generate a cyclizable o-quinone, has been studied. This constant depends on the nature of the monophenol and o-diphenol and is always lower in the presence of the former than of the latter. From the mechanism proposed for tyrosinase and from its kinetic analysis [Rodríguez-López, J. N., Tudela, J., Varón, R., García-Carmona, F. and García-Cánovas, F. (1992) J. Biol. Chem. 267, 3801-3810] a quantitative ratio has been established between the Michaelis constants for oxygen in the presence of monophenols and their o-diphenols. This ratio is used for the determination of the Michaelis constant for oxygen with monophenols when its value cannot be calculated experimentally.
Rodríguez-López
J N
JN
Departamento de Química-Física, E. U. Politécnia de Albacete, Universidad de Castilla-La Mancha.
Ros
J R
JR
Varón
R
R
García-Cánovas
F
F
D001487:Basidiomycota / Q000201:enzymology; D045563:Indolequinones; D007211:Indoles / Q000737:chemistry; D007700:Kinetics; D008956:Models, Chemical; D014442:Monophenol Monooxygenase / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D011048:Polarography; D011809:Quinones / Q000737:chemistry; D013055:Spectrophotometry, Infrared
D045563:Indolequinones; D007211:Indoles; D011809:Quinones; C001123:dopachrome; D014442:Monophenol Monooxygenase; D010100:Oxygen