Activity regulation of tyrosinase by using photoisomerizable inhibitors

Abstract

Enzymatic activity of tyrosinase was controlled on the basis of cis– trans photoisomerization of inhibitors, 4-azobenzene carboxylic acid (ACA) and 4,4′-azobenzene dicarboxylic acid (ADCA). In the case of ACA, the cis form inhibited tyrosinase-catalyzed oxidation of l-tyrosine more strongly than the trans form. On the contrary, in the case of ADCA, the cis form was less inhibitory. The oxidation rate was controlled reversibly by light irradiation in the course of the reaction. In the presence of ACA, UV light irradiation, which isomerized trans to cis form, decelerated the tyrosine oxidation, while visible light irradiation, which isomerized backward, accelerated the reaction. In contrast, in the presence of ADCA, UV light accelerated and visible light decelerated the reaction.