Emond D, Rondeau N, Cedergren R J
Can J Biochem. 1979 Jun;57(6):843-51. doi: 10.1139/o79-104.
The intracellular levels of glutamine synthetase (GS) in Anacystis nidulans grown under different conditions were determined using a whole-cell assay. Nitrate-grown cells have 64% more GS than cells grown in ammonium sulfate. Nitrogen starvation does not affect GS levels appreciably. Incubation of nitrate-grown cells with ammonium sulfate does not change the ratio of gamma-glutamyl transferase activities stimulated by Mg2+ and Mn2+ ions. An in vitro test of adenylylation indicates that algae do not have an endogenous adenylyl transferase (ATase) and that algal GS is not adenylylatable by the Klebsiella aerogenes ATase. Some characteristics of the GS-membrane complex were determined by centrifugation of the complex under varying conditions of pH and ionic strength. In this way, it was shown that acid pH (4.5) stabilizes the complex and high ionic strength tends to solubilize the enzyme. A simple partial purification of GS (89-fold) was developed based on the sedimentation properties of GS.
使用全细胞分析法测定了在不同条件下生长的集胞藻（Anacystis nidulans）中谷氨酰胺合成酶（GS）的细胞内水平。以硝酸盐为氮源生长的细胞中的GS比以硫酸铵为氮源生长的细胞多64%。氮饥饿对GS水平没有明显影响。用硫酸铵培养以硝酸盐为氮源生长的细胞，不会改变由Mg2+和Mn2+离子刺激的γ-谷氨酰转移酶活性的比例。腺苷酸化的体外试验表明，藻类没有内源性腺苷酸转移酶（ATase），并且产气克雷伯菌（Klebsiella aerogenes）的ATase不能使藻类GS发生腺苷酸化。通过在不同pH和离子强度条件下对GS-膜复合物进行离心，确定了该复合物的一些特性。通过这种方式表明，酸性pH（4.5）可使复合物稳定，而高离子强度则倾向于使酶溶解。基于GS的沉降特性，开发了一种简单的GS部分纯化方法（89倍）。
