ORGANIC-ACID ACTIVATION OF THE ALTERNATIVE OXIDASE OF PLANT-MITOCHONDRIA
ORGANIC-ACID ACTIVATION OF THE ALTERNATIVE OXIDASE OF PLANT-MITOCHONDRIA
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DOI：
10.1016/0014-5793(93)80233-k
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发表时间：
1993-08-30
期刊：
影响因子：
3.5
通讯作者：
DAY, DA
中科院分区：
文献类型：
--
作者：
MILLAR, AH;WISKICH, JT;DAY, DA
交替氧化酶活性（在KCN，抗霉素或myxothiazol的存在下的氧摄取）从大豆幼苗的根中分离的线粒体是非常缓慢的，即使与琥珀酸作为底物。通过加入丙酮酸盐，该活性被显著刺激（100-400%），在0.1 mM丙酮酸盐下出现半数最大刺激。从大豆芽线粒体表现出高的交替氧化酶活性与琥珀酸和苹果酸作为底物，但较低的活性与外源性NADH，除了丙酮酸刺激的活性与NADH与琥珀酸。这种对氰化物不敏感的NADH氧化的刺激也见于其他物种的线粒体。羟基丙酮酸和酮戊二酸可以替代丙酮酸，但需要更高的浓度才能达到最大刺激。丙酮酸刺激氰化物不敏感的氧摄取与外源性醌醇作为底物，与亚线粒体颗粒，并在丙酮酸转运抑制剂，氰羟基肉桂酸的存在下，观察到，但没有观察到与洗涤剂溶解的线粒体。这表明丙酮酸对交替氧化酶起变构作用以刺激其活性。这些研究结果在体内呼吸的影响进行了讨论。
Alternative oxidase activity (oxygen uptake in the presence of KCN, antimycin or myxothiazol) in mitochondria isolated from the roots of soybean seedlings was very slow, even with succinate as substrate. This activity was stimulated substantially (100-400%) by the addition of pyruvate, with half maximal stimulation occurring at 0.1 mM pyruvate. Mitochondria from soybean shoots displayed high alternative oxidase activity with succinate and malate as substrates but lower activity with exogenous NADH; addition of pyruvate stimulated the activity with NADH up to that seen with succinate. This stimulation of cyanide-insensitive NADH oxidation was seen also with mitochondria from other species. Hydroxypyruvate and oxoglutarate could substitute for pyruvate, although higher concentrations were required to achieve maximum stimulation. Pyruvate stimulation of cyanide-insensitive oxygen uptake was observed with exogenous quinols as substrates, with sub-mitochondrial particles, and in the presence of the pyruvate transport inhibitor, cyanohydroxycinnamic acid, but was not observed with detergent-solubilised mitochondria. It is suggested that pyruvate acts allosterically on the alternative oxidase to stimulate its activity. The implications of these findings for respiration in vivo are discussed.