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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >A new activity for an old enzyme: Escherichia coli bacterial alkaline phosphatase is a phosphite-dependent hydrogenase.
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A new activity for an old enzyme: Escherichia coli bacterial alkaline phosphatase is a phosphite-dependent hydrogenase.

机译：一种旧酶的新活性：大肠杆菌细菌碱性磷酸酶是一种亚磷酸酯依赖性氢化酶。

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摘要

Genetic analysis indicates that Escherichia coli possesses two independent pathways for oxidation of phosphite (Pt) to phosphate. One pathway depends on the 14-gene phn operon, which encodes the enzyme C-P lyase. The other pathway depends on the phoA locus, which encodes bacterial alkaline phosphatase (BAP). Transposon mutagenesis studies strongly suggest that BAP is the only enzyme involved in the phoA-dependent pathway. This conclusion is supported by purification and biochemical characterization of the Pt-oxidizing enzyme, which was proven to be BAP by N terminus protein sequencing. Highly purified BAP catalyzed Pt oxidation with specific activities of 62-242 milliunits/mg and phosphate ester hydrolysis with specific activities of 41-61 units/mg. Surprisingly, BAP catalyzes the oxidation of Pt to phosphate and molecular H(2). Thus, BAP is a unique Pt-dependent, H(2)-evolving hydrogenase. This reaction is unprecedented in both P and H biochemistry, and it is likely to involve direct transfer of hydride from the substrate to water-derived protons.
机译：遗传分析表明，大肠杆菌具有两个独立的将亚磷酸酯（Pt）氧化为磷酸盐的途径。一种途径取决于14个基因的phn操纵子，该操纵子编码C-P裂解酶。另一个途径取决于phoA基因座，它编码细菌碱性磷酸酶（BAP）。转座子诱变研究强烈表明BAP是参与phoA依赖性途径的唯一酶。 Pt氧化酶的纯化和生化特性支持了这一结论，N端蛋白测序已证明该酶是BAP。高度纯化的BAP催化的Pt氧化具有62-242毫单位/毫克的比活度，而磷酸酯的水解具有41-61单位/毫克的比活度。出人意料的是，BAP催化Pt氧化为磷酸盐和分子H（2）。因此，BAP是一种独特的Pt依赖的H（2）进化氢化酶。该反应在P和H生物化学中都是前所未有的，并且很可能涉及氢化物从底物直接转移到水质子。

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