Towards understanding the mechanisms of proton pumps in Complex-I of the respiratory chain

• 来源期刊: 生物物理学报
• 年，卷（期）: 2019,（5）
• 页码范围: 219-234
• 页数: 16页
• 语种: 中文

摘要

INTRODUCTION Complex-Ⅰ (i.e.,nicotinamide adenine dinucleotide (NADH):ubiquinone (quinone or Q) oxidoreductase) of the respiratory chain is crucial for converting energy from its redox form (i.e.,electron transfer) to the transmembrane electrochemical potential (Hirst 2013;Kaila 2018;Verkhovskaya and Bloch 2013;Walker 1992).Homologs of Complex-Ⅰ are ubiquitously expressed throughout all forms of life,from bacteria to human cells (Friedrich and Scheide 2000).Complex-Ⅰ utilizes the redox energy of the NADH-quinone pair to drive four protons across the membrane (Jones et al.2017).In both the bacteria cytoplasmic membrane as well as the mitochondrial inner membrane,the electrochemical potential of protons (i.e.,proton-motive force,PMF) established by Complex-Ⅰ is found to be always in an inside-alkaline and inside-negative orientation.The energy conversion catalyzed by Complex-Ⅰ is highly efficient,and under near-equilibrium conditions,the process is thermodynamically reversible,characterized by negligible loss of energy through heat.This high efficiency indicates that the redox reaction is tightly coupled to the process of transmembrane-vectorial proton translocation (Hirst 2013;Verkhovskaya and Bloch 2013;Vinogradov 1998).