Puustinen A, Wikström M
Department of Medical Chemistry, University of Helsinki, Finland.
Proc Natl Acad Sci U S A. 1991 Jul 15;88(14):6122-6. doi: 10.1073/pnas.88.14.6122.
Cytochrome o, one of the two terminal ubiquinol oxidases of Escherichia coli, is structurally and functionally related to cytochrome c oxidase of mitochondria and some bacteria. It has two heme groups, one of which binds CO and forms a binuclear oxygen reaction center with copper. The other heme is unreactive toward ligands, exhibits strong interactions with the binuclear center, and is mainly responsible for the reduced-minus-oxidized alpha band. Protoheme has been thought to be the prosthetic group of b-type cytochromes, including cytochrome o. However, the hemes of cytochrome o are of a different kind, for which we propose the name heme O. Its pyridine hemochrome spectrum is blue-shifted by 4 nm relative to that of protoheme, and chromatographic behavior showed that it is much more hydrophobic than protoheme. Fast atom bombardment mass spectrometry yielded a molecular mass of 839 Da. Heme O is proposed to be a heme A-like molecule, containing a 17-carbon hydroxyethylfarnesyl side chain, but with a methyl residue replacing the formyl group.
细胞色素o是大肠杆菌两种末端泛醇氧化酶之一，在结构和功能上与线粒体及某些细菌的细胞色素c氧化酶相关。它有两个血红素基团，其中一个与一氧化碳结合，并与铜形成双核氧反应中心。另一个血红素对配体无反应，与双核中心有强烈相互作用，主要负责还原态减去氧化态的α带。原血红素一直被认为是b型细胞色素（包括细胞色素o）的辅基。然而，细胞色素o的血红素属于不同类型，我们为此提出血红素O这一名称。其吡啶血色原光谱相对于原血红素蓝移了4纳米，色谱行为表明它比原血红素疏水性强得多。快原子轰击质谱法测得其分子量为839道尔顿。血红素O被认为是一种类似血红素A的分子，含有一个17碳的羟乙基法尼基侧链，但用一个甲基残基取代了甲酰基。
