1982 Volume 20 Issue 2 Pages 117-127
The effects of melanogenesis-interrupting syhthetic detergents on the active sites of mushroom tyrosinase were investigated. Contrary to the generally accepted assumption, the catecholase activity was not irreversibly inactivated after the reaction on a large excess of p-tert-butylcatechol. The addition of catechol after the reaction on p-tert-butylcatechol reached a plateau led to further consumption of oxygen. The addition of p-cresol to the reaction system after the enzyme ceased to react on p-tert-butylcatechol also resulted in the oxidation of p-cresol. When catechol was the first substrate, however, further addition of a diphenol (such as p-tert-butylcatechol) or a monophenol (like p-cresol) after completion of the oxidation on catechol brought about no more oxygen uptake. Those two conflicting results could be explained by the assumption that the affinity of the oxidation product(s) of p-tert-butylcatechol to the active sites of cresolase and catecholase was much lower than that of the oxidation product(s) of catechol. In order to minimize occupational hazards (depigmentation), it is recommended that phenolic compounds and their oxidation products first be tested with regard to their degree of inhibition on tyrosinase before these chemicals are handled in factories.
