Egan R M, Phillips A T
J Bacteriol. 1977 Nov;132(2):370-6. doi: 10.1128/jb.132.2.370-376.1977.
Synthesis of the biodegradative L-threonine dehydratase in Escherichia coli, Crookes strain, was prevented by dissolved oxygen concentrations of 6 micrometer or greater. This effect was shown to be exerted solely on synthesis, rather than being the result of enzyme inactivation in vivo. In addition to an anaerobic environment, maximum enzyme synthesis was dependent upon the presence of a complete complement of amino acids, with omission of L-threonine, L-valine, or L-leucine producing the largest decreases in enzyme formation. L-Threonine, the most essential of the amino acid requirements, could be partially replaced by DL-allothreonine or alpha-ketobutyrate. Half-maximal stimulation of enzyme synthesis occurred with 0.4 mM threonine in the medium. The roles of anaerobiosis and amino acids are interpreted as being in accord with the concept that threonine dehydratase functions in anaerobic energy production under conditions of amino acid sufficiency.
在大肠杆菌克鲁克斯菌株中，溶解氧浓度达到6微摩尔或更高时，生物降解型L-苏氨酸脱水酶的合成受到抑制。这种效应仅作用于合成过程，而非体内酶失活的结果。除了厌氧环境外，最大酶合成还依赖于完整氨基酸补充物的存在，缺少L-苏氨酸、L-缬氨酸或L-亮氨酸会使酶形成量最大程度减少。L-苏氨酸是氨基酸需求中最关键的一种，可部分被DL-别苏氨酸或α-酮丁酸替代。培养基中0.4 mM苏氨酸可使酶合成达到最大刺激的一半。厌氧和氨基酸的作用被解释为与苏氨酸脱水酶在氨基酸充足条件下参与厌氧能量产生的概念相符。
