摘要
在分离纯化的基础上,报道了pH、温度和金属离子对林肯链霉菌(Streptomyceslincolnensis)Z-512谷氨酸胺合成酶(GS)活力的影响及GS底物专一性的研究结果.在动力学性质的研究中,发现林肯链霉菌GS在生物合成反应系统中,对底物NH_4CI的饱和曲线不遵守米氏方程.Hill作图呈两相曲线.在NH_4CI浓度低的情况下,Hill系数大于1,具有正协同效应;当NH_4CI浓度增加到一定程度时,Hill系数小于1,具有负协同效应.这说明NH_4CI不仅作为林肯链霉菌GS的底物,而且作为一种效应物调节GS的活性.林肯链霉菌GS对底物Glu及ATP的饱和曲线遵守米氏方程.在不同的激活离子存在下,GS对Glu、ATP的Km值也不同.
Glutamine synthetase from Streptomyces lincolnensis was purified to electrophoretic homogeneity. The effects of pH, temperature and metal ions on the purified enzyme were studied, and the substrate specificity of glutamine synthetase were reported. Under the standard biosynthetic assay system, the substrate saturation curves of glutamine synthetase from Streptomyces lincolnensis for ammonia did not agree with the Michaelis-Menten relationship, with either Mn2+ or Mg2+ as divalent cation, and Hill constants ≠1. The Km values of GS for Glu and ATP were different with different divalent cation.
出处
《微生物学报》
CAS
CSCD
北大核心
1998年第6期441-448,共8页
Acta Microbiologica Sinica
基金
国家"863"计划
国家自然科学基金
关键词
林肯链霉菌
谷氨酰胺合成酶
酶学性质
Streptomyces lincolnensis, Glutamine Synthetase, Characterization
