二价阳离子对巴西固氮螺菌未腺苷酸化谷氨酰胺合成酶催化特性及二级结构的影响。
Influence of divalent cations on the catalytic properties and secondary structure of unadenylylated glutamine synthetase from Azospirillum brasilense.
作者信息
Antonyuk L P, Smirnova V E, Kamnev A A, Serebrennikova O B, Vanoni M A, Zanetti G, Kudelina I A, Sokolov O I, Ignatov V V
机构信息
Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Saratov.
出版信息
Biometals. 2001 Mar;14(1):13-22. doi: 10.1023/a:1016640522299.
Fully unadenylylated glutamine synthetase (GS) from the endophytic bacterium Azospirillum brasilense Sp245 was isolated and purified. The enzyme was electrophoretically homogeneous and contained strongly bound metal ions, which could not be removed by dialysis. Mn2+, Mg2+, and Co2+ were found to be effective in supporting biosynthetic activity of the A. brasilense GS. Some kinetic properties of Mn2+-activated and Mg2+-activated unadenylylated GS were characterized. Circular dichroism analysis of the enzyme showed that the A. brasilense GS is a highly structured protein: 59% of its residues form alpha-helices and 13% beta-strands. Removal of the metal ions from the A. brasilense GS by treatment with EDTA resulted in alterations in the enzyme secondary structure.
从内生细菌巴西固氮螺菌Sp245中分离并纯化了完全未腺苷酸化的谷氨酰胺合成酶（GS）。该酶在电泳上是均一的，并且含有紧密结合的金属离子，这些金属离子不能通过透析去除。发现Mn2 +、Mg2 +和Co2 +对支持巴西固氮螺菌GS的生物合成活性有效。对Mn2 +激活和Mg2 +激活的未腺苷酸化GS的一些动力学特性进行了表征。该酶的圆二色性分析表明，巴西固氮螺菌GS是一种高度结构化的蛋白质：其59%的残基形成α螺旋，13%形成β链。用EDTA处理从巴西固氮螺菌GS中去除金属离子会导致酶二级结构的改变。
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