Hollocher T C
Antonie Van Leeuwenhoek. 1982;48(6):531-44. doi: 10.1007/BF00399539.
Some recent studies on the pathway of nitrogen and the reductases of denitrification are reviewed. The available evidence suggests that while the intermediates of denitrification can remain enzyme-bound (presumably to nitrite reductase) prior to formation of N2O, NO and nitroxyl (HNO) can be released in part by certain bacteria. Release of NO is recognized by a nitrite/NO-15N exchange reaction and isotopic scrambling in product N2O; release of nitroxyl by Pseudomonas stutzeri is recognized by isotopic scrambling of nitrite and NO in product N2O in absence of exchange and affords evidence that the first N-N bond forms in denitrification at the N1+ redox level. The recent purification and partial characterization of nitrous oxide reductase are described. The ability of the dissimilatory nitrite reductase to activate nitrite for nitrosyl transfer affords a new chemical probe into the mechanism of action of this central enzyme. It would appear that reduction of nitrite is subject to electrophilic catalysis. 18O studies show that dissociation of nitrite from nitrite reductase can be slow relative to competing reduction or nitrosyl transfer.
本文综述了近期关于氮途径和反硝化还原酶的一些研究。现有证据表明，虽然反硝化作用的中间产物在形成N2O之前可以保持与酶结合（可能与亚硝酸还原酶结合），但某些细菌可以部分释放NO和硝酰基（HNO）。通过亚硝酸盐/NO-15N交换反应和产物N2O中的同位素重排可以识别NO的释放；在没有交换的情况下，通过产物N2O中亚硝酸盐和NO的同位素重排可以识别施氏假单胞菌释放的硝酰基，这为反硝化作用中第一个N-N键在N1+氧化还原水平形成提供了证据。本文描述了一氧化二氮还原酶最近的纯化和部分特性。异化型亚硝酸还原酶激活亚硝酸盐进行亚硝酰基转移的能力为研究这种核心酶的作用机制提供了一种新的化学探针。似乎亚硝酸盐的还原受到亲电催化作用。18O研究表明，相对于竞争性还原或亚硝酰基转移，亚硝酸盐从亚硝酸还原酶上的解离可能较慢。
