Papa S, Capitanio N, Glaser P, Villani G
Institute of Medical Biochemistry and Chemistry, University of Bari, Italy.
Cell Biol Int. 1994 May;18(5):345-55. doi: 10.1006/cbir.1994.1084.
Proton pumping heme-copper oxidases represent the terminal, energy-transfer enzymes of respiratory chains in prokaryotes and eukaryotes. The CuB-heme a3 (or heme o) binuclear center, associated with the largest subunit I of cytochrome c and quinol oxidases, is directly involved in the coupling between dioxygen reduction and proton pumping. The role of the other subunits is less clear. The following aspects will be covered in this paper: i) the efficiency of coupling in the mitochondrial aa3 cytochrome c oxidase. In particular, the effect of respiratory rate and protonmotive force on the H+/e- stoichiometry and the role of subunit IV; ii) mutational analysis of the aa3 quinol oxidase of Bacillus subtilis addressed to the role of subunit III, subunit IV and specific residues in subunit I; iii) possible models of the protonmotive catalytic cycle at the binuclear center. The observations available suggest that H+/e- coupling is based on the combination of protonmotive redox catalysis at the binuclear center and co-operative proton transfer in the protein.
质子泵血红素 - 铜氧化酶是原核生物和真核生物呼吸链中的末端能量传递酶。与细胞色素c和喹啉氧化酶的最大亚基I相关联的CuB - 血红素a3（或血红素o）双核中心，直接参与了双氧还原与质子泵之间的偶联。其他亚基的作用尚不清楚。本文将涵盖以下几个方面：i）线粒体aa3细胞色素c氧化酶中的偶联效率。特别是呼吸速率和质子动力对H⁺/e⁻化学计量的影响以及亚基IV的作用；ii）针对枯草芽孢杆菌aa3喹啉氧化酶的亚基III、亚基IV和亚基I中特定残基的作用进行的突变分析；iii）双核中心质子动力催化循环的可能模型。现有观察结果表明，H⁺/e⁻偶联基于双核中心的质子动力氧化还原催化与蛋白质中协同质子转移的结合。
