Lin W
Central Research and Development Department, Experimental Station, E. I. du Pont de Nemours and Company, Wilmington, Delaware 19801.
Plant Physiol. 1982 Jul;70(1):326-8. doi: 10.1104/pp.70.1.326.
A plasmalemma-bound NADH oxidation system (Lin 1982 Proc Natl Acad Sci USA 79: 3773-3776) in corn root protoplasts was isolated by a mild treatment of intact protoplasts with trypsin. The majority of NADH stimulated O(2) consumption activity of the protoplasts could be recovered in the supernatant isolated from the intact protoplasts which have been treated with trypsin. The activation energy of NADH oxidation in the supernatant is similar to that of the intact protoplasts (8.7 versus 9.4 kilocalories per mole per degree). Unlike that of the intact protoplasts, an Arrhenius plot of the temperature response (from 5 to 25 degrees C) of the activity in the supernatant shows no transition suggestive of a dissociation of the enzyme from the membrane. Trypsin treatment did not affect K(+) uptake into cell volume of the protoplast. However, the NADH-stimulated K(+) uptake and the increase of cell volume were greatly reduced. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of trichloroacetic acid-precipitated protein from the supernatant showed one extra peptide band with approximately 42 kilodalton molecular weight.
通过用胰蛋白酶对完整原生质体进行温和处理，分离出了玉米根原生质体中一种与质膜结合的NADH氧化系统（林1982年，《美国国家科学院院刊》79: 3773 - 3776）。原生质体中大部分受NADH刺激的氧气消耗活性可在从经胰蛋白酶处理的完整原生质体分离出的上清液中恢复。上清液中NADH氧化的活化能与完整原生质体的相似（每摩尔每度分别为8.7千卡和9.4千卡）。与完整原生质体不同，上清液中活性的温度响应（5至25摄氏度）的阿累尼乌斯图没有显示出表明酶与膜解离的转变。胰蛋白酶处理不影响钾离子进入原生质体的细胞体积。然而，NADH刺激的钾离子摄取和细胞体积的增加大大减少。对上清液中三氯乙酸沉淀蛋白进行的十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳显示出一条额外的肽带，分子量约为42千道尔顿。
