Abstract:

The effects of the quantity of enzyme solution, substrate concentration, temperature and pH on the activity of potato tyrosinase were determined by spectrophotometer method in order to determine the optimal reaction conditions of potato tyrosinase. Along with this, the inhibitory effect of catechins on potato tyrosinase in a Na2HPO4-NaH2PO4 buffer solution (pH 6.8) at 30 ℃ was examined by enzymatic kinetics methods. The optimal conditions for the reaction of potato tyrosinase were found to be adding 0.5 mL of the crude tyrosinase solution extracted from potato to the 2 mmol/L substrate solution for reaction at 30 ℃, pH 6.8. Catechins could inhibit potato tyrosinase, and the concentration for 50% inhibition rate was approximately 0.27 mg/mL. The Lineweaver-Burk plot showed that the inhibitory effect of catechins on potato tyrosinase was competitive, and the inhibition constant (KI) was 0.16 mg/mL.

Key words: tyrosinase, catechins, inhibitory effect, kinetics