Purification and comparison of glutamine synthetase from chicken liver, brain and neural retina

Glutamine synthetase (L-glutamate: ammonia ligase, EC 6.3.1.2) was isolated from chicken liver, brain and neural retina. The specific activities of the purified enzyme preparations from the three different sources were similar. They were composed of subunits of the same molecular weight (43 K) and were immunologically indistinguishable. Slight differences were detectable among them in relation to the amino acid compositions and regulation of their activities by the several effectors tested.