Dimethyl sulfide, a volatile flavor constituent, is a slow-binding inhibitor of tyrosinase.
In this paper, the inhibition of tyrosinase by a volatile compound is kinetically analyzed for the first time. The results obtained show that the volatile flavor constituent dimethyl sulfide (DMS) inhibits the catecholase activity of tyrosinase in a nonclassical manner. A decrease in the initial velocity to a inhibited steady-state velocity can be observed within a few minutes. This time dependence, which is unaltered by prior incubation of the enzyme with the inhibitor, is consistent with a first-order transition. Both the initial and the constant rates decreased with increasing concentrations of inhibitor. The kinetic data obtained correspond to those for a postulated mechanism involving rapid formation of an enzyme-inhibitor complex that subsequently undergoes a relatively slow reversible reaction. These results, together with the high levels of DMS precursor in certain organisms, suggest a physiological role for this compound within plant tissues.
Pérez-Gilabert
M
M
Departamento de Bioquímica y Biología Molecular-A, Facultad de Biología, Universidad de Murcia, Campus de Espinardo, E-30071 Murcia, Spain.
García-Carmona
F
F
D000363:Agaricales / Q000201:enzymology; D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004817:Epidermis / Q000201:enzymology; D005421:Flavoring Agents / Q000494:pharmacology*; D007700:Kinetics; D007980:Levodopa / Q000378:metabolism; D008956:Models, Chemical; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors*; D011485:Protein Binding; D013440:Sulfides / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D005421:Flavoring Agents; D013440:Sulfides; D007980:Levodopa; D014442:Monophenol Monooxygenase; C004784:dimethyl sulfide