Yui Y, Watanabe Y, Ito S, Shizuta Y, Hayaishi O
J Bacteriol. 1977 Nov;132(2):363-9. doi: 10.1128/jb.132.2.363-369.1977.
To determine the inducer(s) of the biodegradative threonine deaminase in Escherichia coli, the effects of various amino acids on the synthesis of this enzyme were investigated. The complex medium used hitherto for the enzyme induction can be completely replaced by a synthetic medium composed of 18 natural amino acids. In this synthetic medium, the omission of each of the seven amino acids threonine, serine, aspartic acid, methionine, valine, leucine, and arginine resulted in the greatest loss of enzyme formation. These seven amino acids did not significantly influence the uptake of other amino acids into the cells. Furthermore, they did not stimulate the conversion of inactive enzyme into an active form, since they did not affect the enzyme level in cells in which protein synthesis was inhibited by chloramphenicol. Threonine, serine, aspartic acid, and methionine failed to stimulate enzyme production in cells in which messenger ribonucleic acid synthesis was arrested by rifampin, whereas valine, leucine, and arginine stimulated enzyme synthesis under the same conditions. Therefore, the first four amino acids appear to act as inducers of the biodegradative threonine deaminase in E. coli and the last three amino acids appear to be amplifiers of enzyme production. The term "multivalent induction" has been proposed for this type of induction, i.e., enzyme induction only by the simultaneous presence of several amino acids.
为了确定大肠杆菌中生物降解性苏氨酸脱氨酶的诱导剂，研究了各种氨基酸对该酶合成的影响。迄今用于酶诱导的复杂培养基可完全由包含18种天然氨基酸的合成培养基替代。在这种合成培养基中，省略苏氨酸、丝氨酸、天冬氨酸、蛋氨酸、缬氨酸、亮氨酸和精氨酸这七种氨基酸中的任何一种，都会导致酶形成的最大损失。这七种氨基酸对其他氨基酸进入细胞的过程没有显著影响。此外，它们不会刺激无活性酶转化为活性形式，因为它们不会影响氯霉素抑制蛋白质合成的细胞中的酶水平。苏氨酸、丝氨酸、天冬氨酸和蛋氨酸在利福平阻止信使核糖核酸合成的细胞中无法刺激酶的产生，而缬氨酸、亮氨酸和精氨酸在相同条件下能刺激酶的合成。因此，前四种氨基酸似乎是大肠杆菌中生物降解性苏氨酸脱氨酶的诱导剂，而后三种氨基酸似乎是酶产生的增强剂。对于这种诱导类型，即仅由几种氨基酸同时存在时进行的酶诱导，已提出“多价诱导”这一术语。
