紫草萘醌类化合物对乳酸脱氢酶和乙醇脱氢酶的共价修饰作用

Covalent Modification of Lactate Dehydrogenase and Alcohol Dehydrogenase by Alkannin Derivatives

为研究紫草萘醌类化合物的细胞毒性作用机制 ,从新疆软紫草根中分离出四种紫草萘醌类化合物 β ,β 二甲基丙烯酰阿卡宁 (1) ,乙酰阿卡宁 (2 ) ,β 乙酰氧基异戊酰阿卡宁 (3)和阿卡宁 (4)。研究了四种天然紫草萘醌类化合物对乳酸脱氢酶和乙醇脱氢酶的共价修饰作用。酶活力测定结果表明 ,这四种紫草萘醌类化合物对两种脱氢酶都具有不同程度的抑制作用 ;酶分子中游离氨基和巯基修饰率的测定结果表明 ,紫草萘醌类化合物对两种酶的抑制作用主要是通过与酶分子中的巯基共价结合产生的。

Covalent modification of four isolated alkannin derivatives (alkannin, acetylalkannin, β, β dimethylacrylalkannin and β acetoxyisovalerylalkannin, respectively) on rabbit muscle latate dehydrogenase (LDHase) and yeast Alcohol Dehydrogenase (ADHase) has been studied. The quinone concentration curves show that the two enzymes are inhibited to different extents by the four alkannin derivatives. Assays of free amino groups and thiol groups in the enzymes indicate that the catalytic activities of LDHase and ADHase are mainly inhibited by covalent reaction of alkannin derivatives with thiol groups in enzymes. These results could be useful for investigating the biological mechanism of alkannin derivatives′ cytotoxicity.