Inhibitory Kinetics of a Trifluoromethyl-Containing 1,2,3-Triazole Derivative on Mushroom Tyrosinase Activity

In this study, we demonstrate that the trifluoromethyl-containing 1,2,3-triazole derivative (TF-TZ) inhibits mushroom tyrosinase. TF-TZ could inhibit the monophenolase and diphenolase activities and the inhibition is reversible. IC50 values of 30.4, and 34.5 mu mol.L-1 were estimated for the monophenolase activity and the diphenolase activity, respectively. TF-TZ could extend the lag period of the monophenolase activity. Kinetic analysis showed that parabolic-competitive inhibition of TF-TZ occurred on diphenolase. We proposed that two TF-TZ molecules combined with free tyrosinase to form enzyme-inhibitor complexes (El and EI2), and the inhibition constants (K-i1, for EI and K-i2 for EI2) were 76.9 and 9.71 mu mol.L-1, respectively. Moreover, the UV-Visible spectrum of a mixture of tyrosinase and TF-TZ exhibited a characteristic shoulder peak that could be assigned to chelation of TF-TZ to the active site.