Herzfeld A, Huang Y Z
Enzyme. 1975;19(2):116-28. doi: 10.1159/000458981.
The purification of glutamine synthetase (GS) from rat liver demonstrates that a small portion of glutamine-hydroxylamine-glutamyltransferase activity (GT) remains associated with GS activity (GT(S)). As GS is purified from the water extract, the ratio between GT(S) activity (GT(T)) is left to be extracted by KC1 from the pellet and, on further purification, appears to be independent of GS activity. Subtle differences in pH optimum, substrate requirement and reaction rates on addition of cofactors and amino acids in vitro and in responses to hormonal stimuli in vivo indicate that the glutamine transfer reaction may be catalyzed by two distinguishable proteins; only the minor component may be identical to GS.
从大鼠肝脏中纯化谷氨酰胺合成酶（GS）表明，一小部分谷氨酰胺-羟胺-谷氨酰转移酶活性（GT）仍与GS活性（GT(S)）相关。当从水提取物中纯化GS时，GT(S)活性（GT(T)）与留在沉淀中有待用KCl提取的活性之比，在进一步纯化时，似乎与GS活性无关。体外添加辅因子和氨基酸时以及体内对激素刺激反应时，在最适pH、底物需求和反应速率方面的细微差异表明，谷氨酰胺转移反应可能由两种不同的蛋白质催化；只有次要成分可能与GS相同。
