Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, Russia.
FEBS J. 2012 Nov;279(21):4052-61. doi: 10.1111/j.1742-4658.2012.08811.x.
Octaheme nitrite reductase from the haloalkaliphilic bacterium Thioalkalivibrio paradoxus was isolated and characterized. A comparative structural and functional analysis of two homologous octaheme nitrite reductases from closely related Thioalkalivibrio species was performed. It was shown that both enzymes have similar catalytic properties, owing to high structural similarity. Both enzymes are characterized by specific structural features distinguishing them from pentaheme cytochrome c nitrite reductases, such as the Tyr-Cys bond in the active site, the hexameric structure resulting in the formation of a void space inside the hexamer, and the product channel that opens into the void interior space of the hexamer. It is suggested that these specific structural features are responsible for the higher nitrite reductase activity, the greater preference for nitrite than for sulfite as a substrate, and the wider pH range of the catalytic activity of octaheme nitrite reductases than of pentaheme homologs.
Nucleotide sequence data are available in the GenBank database under the accession number HQ665012.1. Structural data are available in the RCSB Protein Data Bank database under the accession numbers 3SXQ and 3TTB STRUCTURED DIGITAL ABSTRACT: TvPaR and TvPaR bind by x-ray crystallography (View interaction).
从嗜盐碱性细菌硫代盐单胞菌中分离和表征了八血红素亚硝酸盐还原酶。对两种来自密切相关的硫代盐单胞菌属的同源八血红素亚硝酸盐还原酶进行了比较结构和功能分析。结果表明，由于结构高度相似，两种酶具有相似的催化特性。两种酶都具有独特的结构特征，使其与五血红素细胞色素 c 亚硝酸盐还原酶区分开来，例如活性位点中的 Tyr-Cys 键、六聚体结构导致六聚体内部形成空隙以及通向六聚体内部空隙的产物通道。据推测，这些特定的结构特征负责提高亚硝酸盐还原酶的活性、对亚硝酸盐的更高偏好而非亚硫酸盐作为底物，以及八血红素亚硝酸盐还原酶的催化活性的更宽 pH 范围比五血红素同系物。
核苷酸序列数据可在 GenBank 数据库中以登录号 HQ665012.1 获得。结构数据可在 RCSB 蛋白质数据库中以登录号 3SXQ 和 3TTB 获得。
TvPaR 通过 X 射线晶体学（查看相互作用）结合。
