Korshunov S S, Korkina O V, Ruuge E K, Skulachev V P, Starkov A A
Department of Bioenergetics, A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russia.
FEBS Lett. 1998 Sep 18;435(2-3):215-8. doi: 10.1016/s0014-5793(98)01073-4.
Both natural (laurate) and artificial (m-chlorocarbonylcyanide phenylhydrazone; CCCP) uncouplers strongly inhibit O2.- and H2O2 formation by rat heart mitochondria oxidizing succinate. Carboxyatractylate, an ATP/ADP antiporter inhibitor, abolishes the laurate inhibition, the CCCP inhibition being unaffected. Atractylate partially releases the inhibition by laurate and decelerates the releasing effect of carboxyatractylate. GDP is much less effective than carboxyatractylate in releasing the laurate inhibition of reactive oxygen species (ROS) formation. Micromolar laurate concentrations arresting the ROS formation cause strong inhibition of reverse electron transfer from succinate to NAD+, whereas State 4 respiration and the transmembrane electric potential difference (delta psi) level are affected only slightly. It is suggested that (i) free fatty acids operate as natural 'mild uncouplers' preventing the transmembrane electrochemical H+ potential difference (delta muH+) from being above a threshold critical for ROS formation by complex I and, to a lesser degree, by complex III of the respiratory chain, and (ii) it is the ATP/ADP-antiporter, rather than uncoupling protein 2, that is mainly involved in this antioxidant mechanism of heart muscle mitochondria.
天然解偶联剂（月桂酸）和人工合成解偶联剂（间氯羰基氰化物苯腙；CCCP）均能强烈抑制大鼠心脏线粒体氧化琥珀酸时O₂⁻和H₂O₂的生成。ATP/ADP反向转运体抑制剂羧基苍术苷可消除月桂酸的抑制作用，而CCCP的抑制作用不受影响。苍术苷可部分解除月桂酸的抑制作用，并减缓羧基苍术苷的解除抑制作用。GDP在解除月桂酸对活性氧（ROS）生成的抑制作用方面比羧基苍术苷的效果要差得多。微摩尔浓度的月桂酸抑制ROS生成时，会强烈抑制琥珀酸向NAD⁺的逆向电子传递，而对状态4呼吸和跨膜电位差（Δψ）水平的影响则较小。研究表明：（i）游离脂肪酸作为天然的“轻度解偶联剂”发挥作用，可防止跨膜电化学H⁺电位差（ΔμH⁺）超过呼吸链复合体I以及在较小程度上复合体III生成ROS的临界阈值；（ii）主要参与心肌线粒体这一抗氧化机制的是ATP/ADP反向转运体，而非解偶联蛋白2。
