Numata M, Saito T, Yamazaki T, Fukumori Y, Yamanaka T
Department of Life Science, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology.
J Biochem. 1990 Dec;108(6):1016-21. doi: 10.1093/oxfordjournals.jbchem.a123300.
Cytochrome P-460 of Nitrosomonas europaea [Erickson, R.H. and Hooper, A.B. (1972) Biochim. Biophys. Acta 275, 231-244] was further purified to an electrophoretically homogeneous state. The cytochrome molecule was composed of three molecules of subunits with Mr of 17,300-18,500, and contained three atoms of iron, which seemed to be heme iron, and six cysteine residues, but did not contain nonheme iron or inorganic sulfide. The cytochrome showed absorption peaks at 460 and 688 nm with a broad shoulder at 635 nm in the reduced form. The ESR spectrum of ferricytochrome P-460 showed signals at g = 5.91, 5.63, and 1.99, indicating that the protein was a high spin hemoprotein. The heme of the cytochrome was not cleaved by the methods which were available for cleavage of heme c. The pyridine ferrohemochrome of the hemoprotein did not show the distinct alpha and beta peaks which are shown by the ferrohemochromes of many other cytochromes so far known. The N-terminal amino acid sequence of cytochrome P-460 differed from that of hydroxylamine oxidoreductase. Therefore, cytochrome P-460 did not seem to be the solubilized P-460 moiety of hydroxylamine oxidoreductase, in agreement with the finding by D.J. Miller et al. [J. Gen. Microbiol. 130, 3049-3054 (1984)]. However, cytochrome P-460 had several enzymatic activities which hydroxylamine oxidoreductase showed. Although most of the activities of the cytochrome were lower than the corresponding activities of the oxidoreductase, the hydroxylamine-cytochrome c-552 reductase activity of the cytochrome was about 5-times as high as that of the oxidoreductase.
欧洲亚硝化单胞菌的细胞色素P - 460 [埃里克森，R.H.和胡珀，A.B.（1972年）《生物化学与生物物理学报》275卷，231 - 244页]被进一步纯化至电泳纯状态。细胞色素分子由三个亚基分子组成，其相对分子质量为17,300 - 18,500，含有三个铁原子，似乎是血红素铁，还有六个半胱氨酸残基，但不含非血红素铁或无机硫化物。该细胞色素在还原形式下于460和688 nm处有吸收峰，在635 nm处有一个宽肩峰。高铁细胞色素P - 460的电子顺磁共振谱在g = 5.91、5.63和1.99处显示信号，表明该蛋白质是一种高自旋血红素蛋白。该细胞色素的血红素不能被用于切割血红素c的现有方法所切割。该血红素蛋白的吡啶亚铁血红素没有显示出许多其他已知细胞色素的亚铁血红素所具有的明显的α和β峰。细胞色素P - 460的N末端氨基酸序列与羟胺氧化还原酶的不同。因此，细胞色素P - 460似乎不是羟胺氧化还原酶的可溶P - 460部分，这与D.J.米勒等人[《普通微生物学杂志》130卷，3049 - 3054页（1984年）]的发现一致。然而，细胞色素P - 460具有羟胺氧化还原酶所表现出的几种酶活性。尽管该细胞色素的大多数活性低于氧化还原酶的相应活性，但其羟胺 - 细胞色素c - 552还原酶活性约为氧化还原酶的5倍。
