单个巯基参与大鼠肝脏黄嘌呤氧化还原酶从依赖NAD⁺的活性向依赖O₂的活性的转变过程。
Involvement of a single thiol group in the conversion of the NAD+-dependent activity of rat liver xanthine oxidoreductase to the O2-dependent activity.
作者信息
Kamiński Z W, Jezewska M M
出版信息
Biochem J. 1982 Nov 1;207(2):341-6. doi: 10.1042/bj2070341.
The effects of 2-iodosobenzoic acid, 4-chloromercuribenzoate, 5,5'-dithiobis-(2-nitrobenzoic acid) and tetraethylthioperoxydicarbonic diamide (disulphiram) on the NAD+-dependent activity of xanthine oxidoreductase from rat liver were investigated. Only disulphiram converted the NAD+-dependent activity into the O2-dependent activity quantitatively, without changing the xanthine hydroxylation rate. The modification process was a first-order reaction with respect to time (min) and disulphiram concentration (microM). The kinetic data showed that modification of single thiol group is sufficient for loss of the enzymic activity towards NAD+ as electron acceptor. The complete protection afforded by NAD+ against the action of disulphiram suggests that the essential thiol group may be involved in binding of NAD+ to the xanthine oxidoreductase molecule.
研究了2-碘代苯甲酸、4-氯汞苯甲酸、5,5'-二硫代双-(2-硝基苯甲酸)和四乙基硫代过氧二碳酸二酰胺（双硫仑）对大鼠肝脏黄嘌呤氧化还原酶NAD⁺依赖性活性的影响。只有双硫仑能将NAD⁺依赖性活性定量地转化为O₂依赖性活性，而不改变黄嘌呤羟化速率。修饰过程是关于时间（分钟）和双硫仑浓度（微摩尔）的一级反应。动力学数据表明，单个巯基的修饰足以使酶对作为电子受体的NAD⁺失去活性。NAD⁺对双硫仑作用的完全保护表明，必需的巯基可能参与NAD⁺与黄嘌呤氧化还原酶分子的结合。
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