POST-TRANSLATIONAL ACTIVATION INTRODUCES A FREE-RADICAL INTO PYRUVATE FORMATE-LYASE
POST-TRANSLATIONAL ACTIVATION INTRODUCES A FREE-RADICAL INTO PYRUVATE FORMATE-LYASE
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DOI：
10.1073/pnas.81.5.1332
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发表时间：
1984-01-01
期刊：
影响因子：
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通讯作者：
GANZLER, M
中科院分区：
文献类型：
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作者：
KNAPPE, J;NEUGEBAUER, FA;GANZLER, M
大肠杆菌细胞的丙酮酸甲酸裂解酶（甲酸乙酰转移酶：EC 2.3.1.54）在非活性和活性形式之间进行后转化。非活性形式转化为活性形式是由Fe 2+依赖性活化酶催化的，需要腺苷甲基化酶和二氢黄素氧还蛋白。这个过程在这里显示，以引入一个顺磁性部分的丙酮酸甲酸裂解酶的结构。它在g = 2处显示EPR信号，具有1.5mT的双峰分裂，并且可以包含位于多肽链的氨基酸残基上的有机自由基。次磷酸盐被发现是一种破坏酶自由基和酶活性的特异性试剂;它与蛋白质共价结合。与腺苷甲硫氨酸裂解成5“-脱氧腺苷和甲硫氨酸有关的自由基的酶促生成可能通过Fe-腺苷复合物发生。这些结果表明丙酮酸甲酸裂解酶的催化循环的自由基机制。
Pyruvate formate-lyase (formate acetyltransferase: EC 2.3.1.54) of Escherichia coli cells is post-tanslationally interconverted between inactive and active forms. Conversion of the inactive to the active form is catalyzed by an Fe2+-dependent activating enzyme and requires adenosylmethonine and dihydroflavodoxin. This process is shown here to introduce a paramagnetic moiety into the structure of pyruvate formate-lyase. It displays an EPR signal at g = 2 with a doublet splitting of 1.5 mT and could comprise an organic free radical located on an amino acid residue of the polypeptide chain. Hypophosphite was discovered as a specific reagent that destroys both the enzyme radical and the enzyme activity; it becomes covalently bound to the protein. The enzymatic generation of the radical, which is linked to adenosylmethionine cleavage into 5''-deoxyadenosine and methionine, possibly occurs through an Fe-adenosyl complex. These results suggest a radical mechanism for the catalytic cycle of pyruvate formate-lyase.