The threonine-sensitive homoserine dehydrogenase and aspartokinase activities of Escherichia coli

Biochimica et Biophysica Acta (BBA) - Enzymology and Biological Oxidation Pub Date : 1966-12-14 DOI:10.1016/0926-6593(66)90004-X

Paolo Truffa-Bachi, Gérard Le Bras, Georges N. Cohen

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引用次数: 9

Abstract

1.
1. Homoserine dehydrogenase I (L-homoserine: NADP⁺ oxidoreductase, EC 1.1.1.3) of Escherichia coli is inactivated in two steps by $p- mercuribenzoic$ acid (PMB). The first inactivation step is accompanied by desensitization of the enzyme activity towards its allosteric effector, L-threonine. The desensitized dehydrogenase activity is protected against further action of PMB by its own substrates and by the substrates of the associated activity, aspartokinase I (ATP:L-aspartate 4-phosphotransferase, EC 2.7.2.4).
2.
2. ATP and aspartate, the substrates of the kinase reaction induce conformational changes in the part of the complex enzyme molecule responsible for the dehydrogenase atalytic activity.

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大肠杆菌对苏氨酸敏感的同型丝氨酸脱氢酶和天冬氨酸激酶活性

1.1. 对汞苯甲酸(PMB)分两步灭活大肠杆菌的同型丝氨酸脱氢酶I (L-homoserine: NADP+ oxidoreductase, EC 1.1.1.3)。第一个失活步骤伴随着酶活性对其变构效应物l -苏氨酸的脱敏。脱敏脱氢酶的活性受到其自身底物和相关活性底物天冬氨酸激酶I (ATP: l -天冬氨酸4-磷酸转移酶，EC 2.7.2.4)的保护，免受PMB的进一步作用。ATP和天冬氨酸，激酶反应的底物诱导了负责脱氢酶催化活性的复合酶分子部分的构象变化。

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Biochimica et Biophysica Acta (BBA) - Enzymology and Biological Oxidation

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