Dautry-Varsat A, Cohen G N, Stadtman E R
J Biol Chem. 1979 Apr 25;254(8):3124-8.
Escherichia coli glutamine synthetase is inactivated by subtilisin. Protection against inactivation is afforded by glutamine and ammonium ions. One large fragment (Mr = 35,000) is identified by sodium dodecyl sulfate-gel electrophoresis and carries adenylylation site. Smaller quantities of two other fragments (Mr = 17,000 and 15,000, respectively) are als observed oo observed on the gel. tthe nicked protein remains dodecameric, as evidenced by electrophoresis and centrifugation. It has retained the binding properties toward ADP and Ci-bacron blue and undergoes conformation changes upon binding, as does the intact protein. It is recognized by the antiserum raised against the native enzyme. The nicked protein also remains an excellent substrate of E. coli adenylyltransferase.
大肠杆菌谷氨酰胺合成酶可被枯草杆菌蛋白酶灭活。谷氨酰胺和铵离子可提供对灭活的保护作用。通过十二烷基硫酸钠 - 凝胶电泳鉴定出一个大片段（Mr = 35,000），其带有腺苷酸化位点。在凝胶上还观察到少量另外两个片段（分别为Mr = 17,000和15,000）。经电泳和离心证明，带切口的蛋白质仍为十二聚体。它保留了对ADP和Cibacron blue的结合特性，并且在结合时会发生构象变化，完整蛋白质也是如此。它能被针对天然酶产生的抗血清识别。带切口的蛋白质也是大肠杆菌腺苷酸转移酶的优良底物。
