Richardson D J, Berks B C, Russell D A, Spiro S, Taylor C J
The Centre for Metalloprotein Spectroscopy and Biology, Schools of Biological Sciences and Chemical Sciences, University of East Anglia, Norwich, United Kingdom.
Cell Mol Life Sci. 2001 Feb;58(2):165-78. doi: 10.1007/PL00000845.
Prokaryotic nitrate reduction can serve a number of physiological roles and can be catalysed by a number of biochemically distinct nitrate reductases. Three distinct nitrate reductase classes can be indentified in prokaryotes, NAS, NAR and NAP. NAS is located in the cytoplasmic compartment and participates in nitrogen assimilation. NAR is usually a three-subunit complex anchored to the cytoplasmic face of the membrane with its active site located in the cytoplasmic compartment and is involved in anaerobic nitrate respiration. NAP is a two-subunit complex, located in the periplasmic compartment, that is coupled to quinol oxidation via a membrane anchored tetraheme cytochrome. It shows considerable functional flexibility by participating in anaerobic respiration or redox energy dissipation depending on the organism in which it is found. The members of all three classes of enzymes bind the bis-molybdopterin guanine dinucleotide cofactor at the active site, but they differ markedly in the number and nature of cofactors used to transfer electrons to this site. Analysis of prokaryotic genome sequences available at the time of writing reveals that the different nitrate reductases are phylogenetically widespread.
原核生物的硝酸盐还原可发挥多种生理作用，并且可由多种生物化学性质不同的硝酸盐还原酶催化。在原核生物中可鉴定出三种不同类型的硝酸盐还原酶，即NAS、NAR和NAP。NAS位于细胞质区室，参与氮同化。NAR通常是一个三聚体复合物，锚定在膜的细胞质面，其活性位点位于细胞质区室，参与厌氧硝酸盐呼吸。NAP是一个二聚体复合物，位于周质区室，通过一个膜锚定的四血红素细胞色素与喹啉氧化偶联。根据其所在的生物体，它通过参与厌氧呼吸或氧化还原能量耗散表现出相当大的功能灵活性。所有这三类酶的成员在活性位点结合双钼蝶呤鸟嘌呤二核苷酸辅因子，但它们在用于将电子转移到该位点的辅因子的数量和性质上有显著差异。在撰写本文时对现有原核生物基因组序列的分析表明，不同的硝酸盐还原酶在系统发育上分布广泛。
