KINETICS STUDY OF THE OXIDATION OF 4-TERT-BUTYLPHENOL BY TYROSINASE

Citation
Jr. Ros et al., KINETICS STUDY OF THE OXIDATION OF 4-TERT-BUTYLPHENOL BY TYROSINASE, European journal of biochemistry, 222(2), 1994, pp. 449-452
Citations number
23
Categorie Soggetti
Biology
ISSN journal
00142956
Volume
222
Issue
2
Year of publication
1994
Pages
449 - 452
Database
ISI
SICI code
0014-2956(1994)222:2<449:KSOTOO>2.0.ZU;2-O
Abstract
The reaction between 4-tert-butylphenol (BuPhOH) and mushroom tyrosina se was investigated by following 4-tert-butyl-ortho-benzoquinone, whos e high stability permits the reaction to be used as a model for the st udy of the monophenolase activity of tyrosinase. The system evolves to a pseudo-steady state through an induction period (tau), the pseudo-s teady-state rate (V-ss) decreasing when the (BuPhOH) concentration inc reases. Increases in enzyme concentration result in a parabolic patter n with V-ss, while tau is shortened. The addition of increasing cataly tic amounts of 4-tert-butylcatechol at the start of the reaction reduc es tau until it is totally abolished, an initial burst being observed at high 6-t-butylatechol concentrations. Initial bursts are also obtai ned at pH 4.5 or lower, indicating a lower affinity of the met-tyrosin ase or oxidized form for the monophenol at low pH. These experimental results can be explained by the reaction mechanism of tyrosinase.