肉桂酸甲酯抑制酪氨酸酶催化反应的动力学研究

Kinetics of the inhibition of methyl cinnamate on tyrosinase catalyzed reaction

The inhibitory effects of methyl cinnamate on the monophenolase activity and diphenolase activity of tyrosinase were studied by enzymological kinetic method in Na2HPO4-NaH2PO4 buffer solution(pH=6.8) at 30 ℃.Methyl cinnamate was found to inhibit the monophenolase activity and diphenolase activity of tyrosinase.The methyl cinnamate concentration leading to 50 % inhibitory rate(IC50) were 0.61 mmol/L for monophenolase activity and 1.49 mmol/L for diphenolase activity,respectively.Methyl cinnamate coued extend the lag time of monophenolase.0.8 mmol/L of methyl cinnamate resulted in the lag time extension from 1.1 min to 3.2 min.The inhibition kinetics analyzed by Lineweaver-Burk plots indicated that methyl cinnamate was a noncompetitive inhibitor to diphenolase,and the inhibition constant KI for inhibitor binding with enzyme(E)was 0.66 mmol/L.

The inhibitory effects of methyl cinnamate on the monophenolase activity and diphenolase activity of tyrosinase were studied by enzymological kinetic method in Na2HPO：NaH2PO4 buffer solution （pH = 6. 8） at 30 ℃. Methyl cinnamate was found to inhibit the monophenolase activity and diphenolase activity of tyrosinase. The methyl cinnamate concentration leading to 50 % inhibitory rate （ 1C50 ） were 0.61 mmol/L for monophenolase activity and 1.49 mmol/L for diphenolase activity, respectively. Methyl cinnamate coued extend the lag time of monophenolase. 0.8 mmol/L of methyl cinnamate resulted in the lag time extension from 1.1 min to 3.2 min. The inhibition kinetics analyzed by Lineweaver-Burk plots indicated that methyl cinnamate was a noncompetitive inhibitor to diphenolase, and the inhibition constant K1 for inhibitor binding with enzyme （E）was 0.66 mmol/L.