固氮酶的研究进展

固氮酶将N2还原为NH3的过程是自然界实现氮循环的重要环节。固氮酶是由γ2型二聚体组成的Fe蛋白和α2β2异四聚体组成的MoFe蛋白组成。固氮酶催化的机制包括铁蛋白的氧还循环和钼铁蛋白的氧还循环两部分。Klebsiella pneumoniae的nif基因簇由20个基因组成,构成了8个转录单位,总长度24206bp,其操控机制是多水平、多层次的调控过程。同时综述了固氮酶的多样性,目前已经发现的有钼铁固氮酶、钒铁固氮酶、铁铁固氮酶以及在Strpomyces thermoauophicus内存在的与已知的三种固氮酶体系明显不同的固氮体系。

Advance of study on nitrogenase

The process of nitrogen fixation by nitrogenase is essential for nitrogen circulation in nature. To date, nitrogenase and nitrogen fixation has been well-studied on the level of gene, enzyme, cell and ecosystem. In this review, recentprogress on the structural and functional studies of nitrogenase, nitrogen fixation mechanisms and nifgenes were summarized. The enzymewas composed of two-component metalloproteins called the iron （Fe） protein involvedγ2homodimer and the molybdenum-iron （MoFe） protein involvedα2 β2heterotetramer. The mechanism of Mo-dependent nitrogenase was involved Fe protein cycle and MoFe protein cycle. The complete nucleotide sequence of the Klebsiella pneumoniaegene region fornitrogen fixation （nif） was 24, 206 base-pairs. Coding regions corresponding to the 20 knownnifgenes involved 8 open reading frames could be identified. At the same time, fourknown types ofnitroge-naseswere put forward, and the nitrogenase in Streptomyces thermoautotrophicuswas different from Mo-dependent nitrogenase, V-dependent nitrogenase and Fe-dependent nitrogenase.