对羟基肉桂酸抑制酪氨酸酶活性的动力学研究

采用酶动力学方法研究了对羟基肉桂酸对酪氨酸酶单酚酶和二酚酶活力的抑制效应。结果表明,对羟基肉桂酸对酪氨酸酶单酚酶和二酚酶活性均有抑制作用,导致单酚酶活力和二酚酶活力下降50%的对羟基肉桂酸浓度约分别为0.12 mmol/L和0.50 mmol/L。对羟基肉桂酸能明显延长单酚酶的迟滞时间,0.2 mmol/L对羟基肉桂酸能使迟滞时间由1.1 min延长至6.2 min。对羟基肉桂酸对二酚酶的抑制作用为混合型抑制,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0.29 mmol/L和0.60 mmol/L。

Kinetics of tyrosinase inhibition by 4 - hydroxycinnamic acid

The inhibitory effects of 4-hydroxycinnamic acid on the activity of monophenol oxidase and diphenol oxidase(containing) in tyrosinase were studied using enzymological kinetic method.Experimental results showed that 4-hydroxycinnamic acid can inhibit the activity of monophenol oxidase and diphenol oxidase containing in tyrosinase.The 4-hydroxycinnamic acid concentration that results in 50% activity lost is 0.12 mmol/L for monophenol oxidase activity and(0.50 mmol/L) for diphenol oxidase activity respectively.4-Hydroxycinnamic acid can extend the lag of the action time of monophenol(oxidase).At a concentration of 0.2 mmol/L of 4-hydroxycinnamic acid the lag time will extend from 1.1 min to(6.2 min).The(inhibition) kinetics analyzed by Lineweaver-Burk plots showed that 4-hydroxycinnamic acid is a mixed inhibitor for the(oxidation) of L-DOPA,the equilibrium constants for inhibiting binding with free enzyme and for enzyme-substract(ES)(complex),were 0.29 mmol/L and 0.60 mmol/L respectively.