Hobert E H, Datta P
J Bacteriol. 1983 Aug;155(2):586-92. doi: 10.1128/jb.155.2.586-592.1983.
The specific activity of inducible biodegradative threonine dehydratase (EC 4.2.1.16) in Escherichia coli K-12 increased significantly when the standard tryptone-yeast extract medium or a synthetic mixture of 18 L-amino acids was supplemented with 10 mM KNO3 or 50 mM fumarate and with 4 mM cyclic AMP. In absolute terms, almost four times as much enzyme was produced in the amino acid medium as in the tryptone-yeast extract medium. Enzyme induction in the amino acid medium was sensitive to catabolite repression by glucose, gluconate, glycerol, and pyruvate. An analysis of amino acid requirements for enzyme induction showed that a combination of only four amino acids, threonine, serine, valine, and isoleucine, produced high levels of threonine dehydratase provided that both fumarate and cyclic AMP were present. Immunochemical data revealed that the enzyme synthesized in the presence of these four amino acids was indistinguishable from that produced in the tryptone-yeast extract or the medium with 18 amino acids. We interpret these results to mean that not the amino acids themselves but some metabolites derived anaerobically in reactions involving an electron acceptor may function as putative regulatory molecule(s) in the anaerobic induction of this enzyme.
当标准胰蛋白胨 - 酵母提取物培养基或18种L - 氨基酸的合成混合物中添加10 mM硝酸钾或50 mM富马酸盐以及4 mM环磷酸腺苷时，大肠杆菌K - 12中诱导型生物降解苏氨酸脱水酶（EC 4.2.1.16）的比活性显著增加。从绝对量来看，氨基酸培养基中产生的酶几乎是胰蛋白胨 - 酵母提取物培养基中的四倍。氨基酸培养基中的酶诱导对葡萄糖、葡萄糖酸盐、甘油和丙酮酸的分解代谢阻遏敏感。对酶诱导所需氨基酸的分析表明，只要存在富马酸盐和环磷酸腺苷，仅四种氨基酸（苏氨酸、丝氨酸、缬氨酸和异亮氨酸）的组合就能产生高水平的苏氨酸脱水酶。免疫化学数据显示，在这四种氨基酸存在下合成的酶与在胰蛋白胨 - 酵母提取物或含18种氨基酸的培养基中产生的酶没有区别。我们将这些结果解释为，在涉及电子受体的反应中厌氧衍生的不是氨基酸本身，而是某些代谢物可能作为该酶厌氧诱导中的假定调节分子。
