香草醛对酪氨酸酶活性的抑制

Inhibition of Tyrosinase Activity by Vanillin

在25℃,pH=6.8的Na2HPO4-NaH2PO4缓冲体系中,采用酶动力学方法研究了香草醛对酪氨酸酶单酚酶和二酚酶活性的抑制效应.实验结果表明:香草醛对酪氨酸酶单酚酶和二酚酶活性均有抑制作用,其半数抑制浓度(IC50)约分别为2.7和4.1mmol/L;香草醛能明显延长单酚酶的迟滞时间,4 mmol/L香草醛能使迟滞时间由1.1 m in延长至3m in;Lineweaver-Burk图显示香草醛对二酚酶的抑制作用表现为混合性抑制,对游离酶的抑制常数和对酶-底物络合物的抑制常数分别为3.48和15.1mmol/L.

The inhibitory effect of vanillin on the activities of monophenolase and diphenolase contained in tyrosinase was studied by means of the enzymological kinetic method in a Na2HPO4-NaH2PO4 buffer solution with pH 6.8 at 25 ℃. The results show that the activities of both monophenolase and diphenolase are inhibited by vanillin, with the vanillin concentration leading to 50% of inhibitory rate （IC50） respectively being 2.7 and 4. 1 mmol/L, that vanillin extends the lag time of monophenolase for oxidation from 1.1 to 3 min in a vanillin concentration of 4 mmol/ L, and that the inhibitory effect of vanillin on diphenolase is in a mixed mode, which is proved by Lineweaver-Burk plots. Moreover, the inhibiting constants for the inhibitor binding with free enzyme and enzyme-substrate complex are respectively 3.48 and 15. 1 mmol/L.