维生素B_1对蘑菇酪氨酸酶抑制作用机理的研究

Inhibitory Kinetics and Mechanism of Vitamin B_1 on the Activities of Mushroom Tyrosinase

报道了维生素B1对蘑菇酪氨酸酶的单酚酶和二酚酶活力的影响以及抑制作用机理.研究结果表明,维生素B1(Vit B1)对蘑菇酪氨酸酶的单酚酶和二酚酶活性均有抑制作用.测定导致单酚酶活力和二酚酶活力下降50%的抑制剂浓度(IC50)分别为15和20 mmol/L.Vit B1对蘑菇酪氨酸酶的单酚酶的迟滞时间有明显的延长效应,21 mmol/L Vit B1使得单酚酶的迟滞时间从52 s延长到277 s.Vit B1对二酚酶的抑制作用表现为竞争性抑制类型,测定抑制常数(KI)为11.7 mmol/L.

In this study,the inhibitory mechanism of vitamin B1 on the monophenolase and diphenolase activity of mushroom tyrosinase was investigated. Results showed that vitamin B1 could inhibit both monophenolase activity and diphenolase activity of the en- zyme,and the concentrations lead to 50% loss of activity were 15 and 20 mmol/L,respectively. For the monophenolase activity,vitamin B1 lengthened the lag time and decreased the steady-state activity. With increasing inhibitor concentration,the lag time changed from 52 seconds in its absence to 277 seconds in the presence of 21 mmol/L inhibitor. For the diphenolase activity, the kinetic analysis showed that the inhibition of vitamin B1 on the diphenolase activity of the enzyme was reversible and belonged to competitive-type, and the inhibition constants （K1） were determined to be 11.7 mmol/L.