Rustin P, Lance C
Laboratoire de Biologie Végétale IV (C.N.R.S., U.A. 1180), Université Pierre et Marie Curie, Paris, France.
Biochem J. 1991 Feb 15;274 ( Pt 1)(Pt 1):249-55. doi: 10.1042/bj2740249.
The effects of rotenone on the succinate-driven reduction of matrix nicotinamide nucleotides were investigated in Percoll-purified mitochondria from potato (Solanum tuberosum) tubers. Depending on the presence of ADP or ATP, rotenone caused an increase or a decrease in the level of reduction of the matrix nicotinamide nucleotides. The increase in the reduction induced by rotenone in the presence of ADP was linked to the oxidation of the malate resulting from the oxidation of succinate. Depending on the experimental conditions, malic enzyme (at pH 6.6 or in the presence of added CoA) or malate dehydrogenase (at pH 7.9) were involved in this oxidation. At pH 7.9, the oxaloacetate produced progressively inhibited the succinate dehydrogenase. In the presence of ATP the production of oxaloacetate was stopped, and succinate dehydrogenase was protected from inhibition by oxaloacetate. However, previously accumulated oxaloacetate transitorily decreased the level of the reduction of the NAD+ driven by succinate, by causing the reversal of the malate dehydrogenase reaction. Under these conditions (i.e. presence of ATP), rotenone strongly inhibited the reduction of NAD+ by succinate-driven reverse electron flow. No evidence for an active reverse electron transport through a rotenone-insensitive path could be obtained. The inhibitory effect of rotenone was masked if malate had previously accumulated, owing to the malate-oxidizing enzymes which reduced part or all of the matrix NAD+.
在从马铃薯（Solanum tuberosum）块茎中通过Percoll纯化的线粒体中，研究了鱼藤酮对琥珀酸驱动的基质烟酰胺核苷酸还原的影响。根据ADP或ATP的存在情况，鱼藤酮会导致基质烟酰胺核苷酸还原水平的升高或降低。在ADP存在下，鱼藤酮诱导的还原增加与琥珀酸氧化产生的苹果酸的氧化有关。根据实验条件，苹果酸酶（在pH 6.6或添加CoA的情况下）或苹果酸脱氢酶（在pH 7.9时）参与了这种氧化反应。在pH 7.9时，产生的草酰乙酸逐渐抑制琥珀酸脱氢酶。在ATP存在下，草酰乙酸的产生停止，琥珀酸脱氢酶受到保护，免受草酰乙酸的抑制。然而，先前积累的草酰乙酸通过导致苹果酸脱氢酶反应的逆转，暂时降低了由琥珀酸驱动的NAD⁺还原水平。在这些条件下（即存在ATP），鱼藤酮强烈抑制由琥珀酸驱动的反向电子流引起的NAD⁺还原。没有证据表明存在通过鱼藤酮不敏感途径的活跃反向电子传输。如果先前积累了苹果酸，鱼藤酮的抑制作用会被掩盖，这是由于苹果酸氧化酶会还原部分或全部基质NAD⁺。
