Muriana F J, Relimpio A M
Department of Biochemistry, Faculty of Pharmacy, University of Seville, Spain.
J Biochem. 1993 Jun;113(6):738-41. doi: 10.1093/oxfordjournals.jbchem.a124113.
Partially purified glutamine synthetase from rat liver underwent rapid inactivation upon incubation with NADH and benzyl viologen, under aerobic conditions. This in vitro inactivation was prevented by catalase or chelating-agents, which suggests that hydrogen peroxide and metal ions are involved in the process. Similar inactivation was observed when the rat liver glutamine synthetase was preincubated, under anaerobic conditions, with NADH and benzyl viologen, and hydrogen peroxide was added to the reaction mixture. A radical scavenger, histidine, partially prevents the inactivation, while hydrogen peroxide shows a low inactivation capacity when incubated without NADH. Furthermore, the fact that the inactivation can also be catalyzed by a model consisting of ferrous ions and hydrogen peroxide leads to the conclusion that hydroxyl radicals, or something with similar reactivity, are most likely produced through a Fenton reaction.
在有氧条件下，用NADH和苄基紫精孵育时，大鼠肝脏部分纯化的谷氨酰胺合成酶会迅速失活。过氧化氢酶或螯合剂可阻止这种体外失活，这表明过氧化氢和金属离子参与了该过程。当大鼠肝脏谷氨酰胺合成酶在厌氧条件下与NADH和苄基紫精预孵育，然后向反应混合物中加入过氧化氢时，也观察到了类似的失活现象。一种自由基清除剂组氨酸可部分阻止失活，而过氧化氢在不与NADH一起孵育时失活能力较低。此外，由亚铁离子和过氧化氢组成的模型也能催化失活，这一事实得出的结论是，羟基自由基或具有类似反应活性的物质很可能是通过芬顿反应产生的。
