锰离子（Mn2+）和镁离子（Mg2+）与蜡样芽孢杆菌谷氨酰胺合成酶活性位点的独立结合

Independent bindings of Mn2+ and Mg2+ to the active site of B. cereus glutamine synthetase.

作者信息

Nakano Y, Kimura K

出版信息

Biochem Biophys Res Commun. 1987 Jan 30;142(2):475-82. doi: 10.1016/0006-291x(87)90299-3.

Abstract

Glutamine synthetase purified from Bacillus cereus IFO 3131 was modified by iodoacetamide and the ATP analog 5'-p-fluorosulfonylbenzoyladenosine (FSBA). Only Mg2+-dependent activity was inactivated by iodoacetamide, whereas only Mn2+-dependent activity was inactivated by FSBA. When iodoacetamide-treated enzyme was reacted with FSBA, Mn2+-dependent activity was also inactivated. Mg2+ plus Mn2+-dependent activity was inactivated in any case. The results suggested that the binding sites of Mn2+ and Mg2+ are separate from each other in the active site of B. cereus glutamine synthetase and that bindings of Mg2+ and Mn2+ to each site are required for normal activity in vivo.

摘要

从蜡样芽孢杆菌IFO 3131中纯化得到的谷氨酰胺合成酶，用碘乙酰胺和ATP类似物5'-对氟磺酰苯甲酰腺苷（FSBA）进行修饰。只有依赖Mg2+的活性被碘乙酰胺灭活，而只有依赖Mn2+的活性被FSBA灭活。当用碘乙酰胺处理过的酶与FSBA反应时，依赖Mn2+的活性也被灭活。在任何情况下，依赖Mg2+加Mn2+的活性都被灭活。结果表明，在蜡样芽孢杆菌谷氨酰胺合成酶的活性位点中，Mn2+和Mg2+的结合位点彼此分开，并且Mg2+和Mn2+与每个位点的结合是体内正常活性所必需的。