Capitanio Nazzareno, Palese Luigi Leonardo, Capitanio Giuseppe, Martino Pietro Luca, Richter Oliver-Matthias H, Ludwig Bernd, Papa Sergio
Department of Biomedical Science, University of Foggia, Foggia, Italy.
Biochim Biophys Acta. 2012 Apr;1817(4):558-66. doi: 10.1016/j.bbabio.2011.11.003. Epub 2011 Nov 10.
In this paper allosteric interactions in protonmotive heme aa(3) terminal oxidases of the respiratory chain are dealt with. The different lines of evidence supporting the key role of H(+)/e(-) coupling (redox Bohr effect) at the low spin heme a in the proton pump of the bovine oxidase are summarized. Results are presented showing that the I-R54M mutation in P. denitrificans aa(3) oxidase, which decreases by more than 200mV the E(m) of heme a, inhibits proton pumping. Mutational amino acid replacement in proton channels, at the negative (N) side of membrane-inserted prokaryotic aa(3) oxidases, as well as Zn(2+) binding at this site in the bovine oxidase, uncouples proton pumping. This effect appears to result from alteration of the structural/functional device, closer to the positive, opposite (P) surface, which separates pumped protons from those consumed in the reduction of O(2) to 2 H(2)O.
本文探讨了呼吸链质子动力血红素aa(3)末端氧化酶中的变构相互作用。总结了支持低自旋血红素a处的H(+)/e(-)偶联（氧化还原玻尔效应）在牛氧化酶质子泵中起关键作用的不同证据线索。给出的结果表明，反硝化假单胞菌aa(3)氧化酶中的I-R54M突变使血红素a的E(m)降低了200多毫伏，抑制了质子泵浦。在膜插入的原核aa(3)氧化酶的负（N）侧质子通道中的突变氨基酸置换，以及牛氧化酶中该位点的Zn(2+)结合，使质子泵浦解偶联。这种效应似乎是由靠近正的、相对的（P）表面的结构/功能装置改变引起的，该装置将泵出的质子与还原O(2)为2H(2)O所消耗的质子分开。
