Yoshida T, Fee J A
J Biol Chem. 1984 Jan 25;259(2):1031-6.
Cytochrome oxidase from T. thermophilus is isolated as a noncovalent complex of cytochromes c1 and aa3 in which the four redox components of aa3 appear to be associated with a single approximately 55,000-D subunit while the heme C is associated with a approximately 33,000-D peptide (Yoshida, T., Lorence, R. M., Choc, M. G., Tarr, G. E., Findling, K. L., and Fee, J. A. (1983) J. Biol. Chem. 258, 112-123). We have examined the steady state transfer of electrons from ascorbate to oxygen by cytochrome c1aa3 as mediated by horse heart, Candida krusei, and T. thermophilus (c552) cytochromes c as well as tetramethylphenylenediamine (TMPD). These mediators exhibit simple Michaelis-Menten kinetic behavior yielding Vmax and KM values characteristic of the experimental conditions. Three classes of kinetic behavior were observed and are qualitatively discussed in terms of a reaction scheme. The data show that tetramethylphenyldiamine and cytochromes c react with the enzyme at independent sites; it is suggested that cytochrome c1 may efficiently transfer electrons to cytochrome aa3. When incorporated into phospholipid vesicles, the highly purified cytochrome c1aa3 was found to translocate one proton into the exterior medium for each molecule of cytochrome c552 oxidized. The combined results suggest that this bacterial enzyme functions in a manner generally identical with the more complex eucaryotic enzyme.
嗜热栖热菌的细胞色素氧化酶是以细胞色素c1和aa3的非共价复合物形式分离得到的，其中aa3的四个氧化还原成分似乎与一个约55,000道尔顿的单一亚基相关联，而血红素C则与一个约33,000道尔顿的肽相关联（吉田，T.，洛伦斯，R. M.，乔克，M. G.，塔尔，G. E.，芬德林，K. L.，和费，J. A.（1983年）《生物化学杂志》258，112 - 123）。我们研究了由马心、克鲁斯假丝酵母和嗜热栖热菌（c552）细胞色素c以及四甲基对苯二胺（TMPD）介导的电子从抗坏血酸到氧气的稳态转移过程。这些介导物表现出简单的米氏动力学行为，产生了实验条件下特有的Vmax和KM值。观察到了三类动力学行为，并根据反应方案进行了定性讨论。数据表明，四甲基对苯二胺和细胞色素c在酶的不同位点发生反应；有人提出细胞色素c1可能有效地将电子转移给细胞色素aa3。当高度纯化的细胞色素c1aa3掺入磷脂囊泡中时，发现每氧化一分子细胞色素c552，就有一个质子转运到外部介质中。综合结果表明，这种细菌酶的功能方式与更复杂的真核酶大致相同。
