Kadenbach B, Reimann A, Stroh A, Hüther F J
Fachbereich Chemie der Philipps-Universität, Marburg, Fed. Rep. Germany.
Prog Clin Biol Res. 1988;274:653-68.
The current view on the regulatory function of nuclear-encoded subunits of cytochrome c oxidase from higher evolved organisms is presented. The activity of monomeric laurylmaltoside-dissolved, but not of reconstituted cytochrome c oxidase, is strongly affected by anions accompanied by a conformational change of the enzyme, as shown by changed visible spectra. Addition of uncoupler to proteoliposomes induces the same anion sensitivity as obtained with the soluble enzyme, suggesting dissociation of the dimeric membrane-bound enzyme by uncoupler. Nucleotides are suggested to regulate cytochrome c oxidase activity at 3 different sites: 1) Interaction of ATP with a cytosolic site (outside) increases the Km for cytochrome c in the enzyme from bovine heart and Paracoccus denitrificans; 2) binding of ADP at a matrix site decreases, and 3) binding of ATP at another matrix site increases the Km for cytochrome c of the mammalian enzyme.
本文介绍了关于高等进化生物细胞色素c氧化酶核编码亚基调节功能的当前观点。如可见光谱变化所示，单体月桂基麦芽糖苷溶解的细胞色素c氧化酶（而非重组细胞色素c氧化酶）的活性受阴离子强烈影响，并伴随酶的构象变化。向蛋白脂质体中添加解偶联剂会诱导出与可溶性酶相同的阴离子敏感性，这表明解偶联剂会使二聚体膜结合酶解离。核苷酸被认为在3个不同位点调节细胞色素c氧化酶活性：1）ATP与胞质位点（外部）的相互作用会增加牛心和反硝化副球菌中该酶对细胞色素c的米氏常数；2）ADP在基质位点的结合会降低其活性，以及3）ATP在另一个基质位点的结合会增加哺乳动物酶对细胞色素c的米氏常数。
