摘要
酪氨酸酶是生物体合成黑色素的关键酶.实验发现:5-甲氧基水杨醛对酪氨酸酶的单酚酶和二酚酶活力均有抑制作用;5-甲氧基水杨醛对酪氨酸酶单酚酶活力的影响表现为对酶稳态活力的抑制作用,和对迟滞时间的延长作用,2.0mmol/L的5-甲氧基水杨醛使得单酚酶的稳态酶活力下降68%,并使迟滞时间从107 s延长到160 s;对二酚酶的抑制作用为可逆效应,半抑制率(IC50)为2.45 mmol/L,抑制类型表现为混合型机理,其抑制常数KI和KIS分别为1.426和7.766 mmol/L.通过研究5-甲氧基水杨醛对酪氨酸酶的抑制作用机理,为进一步研究设计新型酪氨酸酶抑制剂奠定基础.
Tyrosinase （1.14. 18.1）, widely distributed in nature.catalyzes both the hydroxylation of monophenols to o-diphenols and the oxidation of o-diphenols to o-quinones. The active site of this enzyme consists of two copper atoms and the enzyme has three states： Emet ,Edeoxy and Eoxy. It is the key enzyme of melanin biosynthesis. The inhibition kinetics and mechanism of the enzyme by 5- methoxysalicylaldehyde were studied and the results showed that 5-methoxysalicylaldehyde not only inhibited steady-state activity of the monophenolase,but also prolonged the lag time of the enzyme. With the concentration of this inhibitor increasing,the activity of the diphenolase reduces exponentially. The inhibitor concentration leading to 50% activity lost （IC50） was estimated to be 0.76 mmol/L for monophenolase activity and 2.45 mmol/L for diphenolase,respectively. They both were more potent than that of 4-methoxysalicylaldehyde. The results showed that the inhibition of 5-methoxysalicylaldehyde on diphenolase was a reversible reaction. The inhibition kinetics analyzed by Lineweaver-Burk plots showed that 5-methoxysalicylaldehyde was a mixed type inhibitor,and the inhibition constants for free enzyme （K1） and for the enzyme-substrate complex （K1s） were determined to be 1. 426 and 7. 766 mmol · L^-l ,respectively.
出处
《厦门大学学报（自然科学版）》
CAS
CSCD
北大核心
2007年第1期87-90,共4页
Journal of Xiamen University：Natural Science
基金
国家自然科学基金(30570408)
化学生物学福建省重点实验室开发课题基金资助
