Colombo G, Villafranca J J
J Biol Chem. 1986 Aug 15;261(23):10587-91.
Glutamine synthetase is encoded by the glnA gene of Escherichia coli and catalyzes the formation of glutamine from ATP, glutamate, and ammonia. A 1922-base pair fragment from a cDNA containing the glnA structural gene for E. coli glutamine synthetase has been sequenced. An open reading frame of 1404 base pairs encodes a protein of 468 amino acid residues with a calculated molecular weight of 51,814. With few exceptions, the amino acid sequence deduced from the DNA sequence agreed very well with the amino acid sequences of several peptides reported previously. The secondary structure predicted for the E. coli enzyme has approximately 36% of the residues in alpha-helices which is in agreement with calculations of approximately 39% based on optical rotatory dispersion data. Comparison of the amino acid sequences of glutamine synthetase from E. coli (468 amino acids) and Anabaena (473 amino acids) (Turner, N. E., Robinson, S. T., and Haselkorn, R. (1983) Nature 306, 337-342) indicates that 260 amino acids are identical and 80 are of the same type (polar or nonpolar) when aligned for maximum homology. Several homologous regions of these two enzymes exist, including the sites of adenylylation and oxidative modification, but the regulation of each enzyme is different.
谷氨酰胺合成酶由大肠杆菌的glnA基因编码，催化由ATP、谷氨酸和氨形成谷氨酰胺。已对包含大肠杆菌谷氨酰胺合成酶glnA结构基因的cDNA的一个1922个碱基对的片段进行了测序。一个1404个碱基对的开放阅读框编码一个由468个氨基酸残基组成的蛋白质，计算分子量为51,814。除少数例外，从DNA序列推导的氨基酸序列与先前报道的几种肽的氨基酸序列非常吻合。预测的大肠杆菌酶的二级结构约有36%的残基处于α-螺旋中，这与基于旋光色散数据计算的约39%一致。对大肠杆菌（468个氨基酸）和鱼腥藻（473个氨基酸）的谷氨酰胺合成酶的氨基酸序列进行比较（特纳，N.E.，罗宾逊，S.T.，和哈塞尔科恩，R.（1983年）《自然》306，337 - 342）表明，当为最大同源性进行比对时，有260个氨基酸是相同的，80个是同一类型（极性或非极性）。这两种酶存在几个同源区域，包括腺苷酸化和氧化修饰位点，但每种酶的调节方式不同。
