Ito J, Yanofsky C
J Bacteriol. 1969 Feb;97(2):734-42. doi: 10.1128/jb.97.2.734-742.1969.
The properties of the anthranilate synthetase complex and its separated subunits were compared in catalyzing the anthranilate synthetase reaction, chorismate + l-glutamine or NH(4) (+) --> anthranilate, and the transferase reaction, anthranilate + 5'-phosphorylribosyl-1-pyrophosphate --> phosphoribosyl anthranilate. It is shown that anthranilate synthetase component I is activated by normal anthranilate synthetase component II, a component II(CRM) (CRM = immunologically cross-reacting material), and by a presumed fragment of component II produced by a deletion mutant. Significant differences between the complex and its subunits are demonstrated with respect to substrate affinity, thermostability, feedback inhibitor sensitivity, and activity in the presence of various divalent cations. Of particular interest are the findings that the transferase activity of component II is only inhibitable by l-tryptophan when the component is in the complex and that this inhibition does not appear to depend upon the feedback-sensitive site of component I.
比较了邻氨基苯甲酸合成酶复合物及其分离的亚基在催化邻氨基苯甲酸合成酶反应（分支酸 + L - 谷氨酰胺或NH₄⁺→邻氨基苯甲酸）和转移酶反应（邻氨基苯甲酸 + 5'-磷酸核糖 - 1 - 焦磷酸→磷酸核糖邻氨基苯甲酸）中的特性。结果表明，邻氨基苯甲酸合成酶组分I可被正常的邻氨基苯甲酸合成酶组分II、一种组分II(CRM)（CRM = 免疫交叉反应物质）以及由缺失突变体产生的假定的组分II片段激活。在底物亲和力、热稳定性、反馈抑制剂敏感性以及在各种二价阳离子存在下的活性方面，复合物及其亚基之间存在显著差异。特别值得关注的发现是，只有当组分II处于复合物中时，其转移酶活性才会被L - 色氨酸抑制，并且这种抑制似乎不依赖于组分I的反馈敏感位点。
