Fachbereich Biologie, Universität Kaiserslautern, Pfaffenbergstraße, D-6750, Kaiserslautern, Federal Republic of Germany.
Planta. 1980 Feb;147(5):477-84. doi: 10.1007/BF00380191.
The intracellular distribution of enzymes involved in the Crassulacean acid metabolism (CAM) has been studied in Bryophyllum calycinum Salisb. and Crassula lycopodioides Lam. After separation of cell organelles by isopycnic centrifugation, enzymes of the Crassulacean acid metabolism were found in the following cell fractions: Phosphoenolpyruvate carboxylase in the chloroplasts; NAD-dependent malate dehydrogenase in the mitochondria and in the supernatant; NADP-dependent malate dehydrogenase and phosphoenolpyruvate carboxykinase in the chloroplasts; NADP-dependent malic enzyme in the supernatant and to a minor extent in the chloroplasts; NAD-dependent malic enzyme in the supernatant and to some degree in the mitochondria; and pyruvate; orthophosphate dikinase in the chloroplasts. The activity of the NAD-dependent malate dehydrogenase was due to three isoenzymes separated by (NH4)2SO4 gradient solubilization. These isoenzymes represented 17, 78, and 5% of the activity recovered, respectively, in the order of elution. The isoenzyme eluting first was associated with the mitochondria and the second isoenzyme was of cytosolic origin, while the intracellular location of the third isoenzyme was probably the peroxisome. Based on these findings, the metabolic path of Crassulacean acid metabolism within cells of CAM plants is discussed.
已对景天酸代谢（CAM）相关酶在落地生根（Bryophyllum calycinum Salisb.）和落地生根（Crassula lycopodioides Lam.）中的细胞内分布进行了研究。通过等密度离心分离细胞器后，在以下细胞部分发现了 CAM 相关酶：磷酸烯醇丙酮酸羧化酶存在于叶绿体中；NAD 依赖性苹果酸脱氢酶存在于线粒体和上清液中；NADP 依赖性苹果酸脱氢酶和磷酸烯醇丙酮酸羧激酶存在于叶绿体中；NADP 依赖性苹果酸酶存在于上清液中，少量存在于叶绿体中；NAD 依赖性苹果酸酶存在于上清液中，在一定程度上存在于线粒体中；以及丙酮酸； orthophosphate dikinase 存在于叶绿体中。NAD 依赖性苹果酸脱氢酶的活性归因于通过（NH4）2SO4 梯度溶解分离的三种同工酶。这些同工酶分别占洗脱顺序中回收活性的 17%、78%和 5%。首先洗脱的同工酶与线粒体有关，第二种同工酶起源于细胞质，而第三种同工酶的细胞内位置可能是过氧化物酶体。基于这些发现，讨论了 CAM 植物细胞内景天酸代谢的代谢途径。
