Abstract：
We recently proposed a diffusible reactive (oxygen) species (DRS/DROS) based function for cytochrome b complexes (CBC) and quinones (Q)/quinols (QH2 ) in the murburn model of bioenergetics. This proposal is in direct conflict with the classical purview of Q-cycle. Via extensive analyses of the structure-function correlations of membrane-quinones/quinols and proteins, we present qualitative and quantitative arguments to infer that the classical model cannot explain the energetics, kinetics, mechanism and probabilistic considerations. Therefore, it is proposed that Q-cycle is neither necessary nor feasible at CBCs. In contrast, we substantiate that the murburn model explains: (a) crucial structural data of CBCs, (b) why quinones/quinols are utilized in bioenergetic membranes, (c) how trans-membrane potential is generated owing to effective charge separation at CBCs, (d) mobility data of O2 , DRS, Q/QH2 , and (e) utility of other reaction/membrane components. Further, the murburn model also accommodates the absence of quinones in anaerobic Archaea, wherein methanophenazines are prevalent. The work mandates that the textbooks and research agendas are refreshed to reflect the new perception. SIGNIFICANCE: The current article must be seen as a critical and detailed analysis of the role and working mechanism of quinone (Q) /quinols (QH2 ) in bioenergetic membranes. In the classical model, QH2 are perceived as highly mobile electron-transport agents that bind and donate electrons to cytochrome b complexes (CBCs), using sophisticated electronic circuitries, in order to recycle Q and pump protons. The classical perception sees radicals (such as Q*-, O2 *-, etc., also called diffusible reactive species, DRS) as wasteful or toxic (patho) physiological manifestations. It is highlighted herein that QH2 has low mobility and matrix has little protons to pump. New insights from the structural analyses of diverse CBCs and quinols, in conjunction with murburn reaction thermodynamics suggest that the electrons from substrates/quinols are effectively utilized via DRS. This perception fits into a much broader analysis of 1 and 2 electron transfers in overall redox metabolism, as recently brought out by the murburn model, wherein DRS are considered obligatory ingredients of physiology. Thus, the findings mandate a reorientation in the pertinent research field.
摘要：
我们最近在生物能量学的murburn模型中提出了基于细胞色素b复合物（CBC）和醌（Q）/醌（QH2）的可扩散反应性（氧）物质（DRS/DROS）功能。该提议与Q循环的经典权限直接冲突。通过对膜醌/喹啉和蛋白质的结构-功能相关性的广泛分析，我们提出了定性和定量的论点来推断经典模型无法解释能量学，动力学,机制和概率考虑。因此,建议Q周期在CBCs既没有必要也不可行。相比之下,我们证实了穆尔本模型解释：(A)CBCs的关键结构数据，(B)为什么醌/喹啉被用于生物膜，（c）由于CBCs的有效电荷分离，跨膜电位是如何产生的，(d)O2的移动性数据，DRS,Q/QH2,和(e)其它反应/膜组分的应用。Further,Murburn模型还适应了厌氧古细菌中醌的缺失，其中甲苯胺是普遍存在的。工作要求更新教科书和研究议程，以反映新的看法。意义：本文必须被视为对醌（Q）/喹啉（QH2）在生物能量膜中的作用和工作机制的关键和详细分析。在经典模型中,QH2被认为是高度移动的电子传输剂，可将电子结合并提供给细胞色素b复合物（CBC），使用复杂的电子电路，为了回收Q和泵质子。经典感知看到自由基(如Q*-，O2*-,等。,也称为可扩散反应物质，DRS）作为浪费或有毒（病理）的生理表现。在本文中强调,QH2具有低迁移率,并且基质具有很少的质子来泵送。来自不同CBCs和喹啉的结构分析的新见解，结合murburn反应热力学表明，通过DRS有效利用了底物/喹啉的电子。这种看法适合更广泛的分析1和2电子转移在整体氧化还原代谢，正如最近由Murburn模型提出的那样，其中DRS被认为是生理的强制性成分。因此，这些发现要求在相关研究领域重新定位。
