关于2'-脱氧尿苷酸羟甲基化酶的作用机制。

On the mechanism of 2'-deoxyuridylate hydroxymethylase.

作者信息

Kunitani M G, Santi D V

出版信息

Biochemistry. 1980 Apr 1;19(7):1271-5. doi: 10.1021/bi00548a001.

Abstract

dUMP hydroxymethylase from SP01-infected Bacillus subtilis has been purified 160-fold by chromatography on DEAE-cellulose and ethylagarose. The enzyme catalyzes exchange of the 5-hydrogen of dUMP for protons of water in the presence or absence of the cofactor CH2-H4folate. Upon treatment with FdUMP and CH2-H4folate, an isolable covalent complex is formed which is believed to be structurally similar to a steady-state intermediate of the normal reaction. The FdUMP-CH2-H4folate-dUMP hydroxymethylase complex is stable toward denaturation with sodium dodecyl sulfate and shows a subunit molecular weight of 46 000. By analogy with chemical models and studies of dTMP synthetase, a mechanism is proposed for the reaction catalyzed by dUMP hydroxymethylase.

摘要

通过在DEAE-纤维素和乙基琼脂糖上进行色谱分离，已将来自被SP01感染的枯草芽孢杆菌的dUMP羟甲基化酶纯化了160倍。该酶在存在或不存在辅因子CH2-H4叶酸的情况下，催化dUMP的5-氢与水中的质子进行交换。用FdUMP和CH2-H4叶酸处理后，会形成一种可分离的共价复合物，据信其结构与正常反应的稳态中间体相似。FdUMP-CH2-H4叶酸-dUMP羟甲基化酶复合物对十二烷基硫酸钠变性具有稳定性，其亚基分子量为46000。通过与化学模型和dTMP合成酶的研究进行类比，提出了dUMP羟甲基化酶催化反应的机制。