Lehner K, Heldt H W
Biochim Biophys Acta. 1978 Mar 13;501(3):531-44. doi: 10.1016/0005-2728(78)90119-6.
The uptake of radioactively labeled dicarboxylates into the sorbitol-impermeable 3H2O space (the space surrounded by the inner envelope membrane) of spinach chloroplasts has been studied by means of silicone layer filtering centrifugation. 1. Malate, aspartate and a number of other dicarboxylates are rapidly transported across the envelope leading to an accumulation in the chloroplasts. This uptake proceeds mainly by a counterexchange with the dicarboxylates present there. 2. The dicarboxylate transport shows saturation characteristics allowing the determination of Km and V. 3. All dicarboxylates transported act as competitive inhibitors of the transport. 4. The activation energy of the transport as determined from the temperature dependency is evaluated to be 7 kcal/mol. 5. The rate of dicarboxylate transport is influenced by illumination, the countertransported molecules and the pH in the medium. These changes effect the transport velocity, whereas the corresponding Km values are not altered. 6. It is discussed whether there is more than one carrier involved in dicarboxylate transport in spinach chloroplasts.
利用硅胶层过滤离心法，研究了放射性标记的二羧酸进入菠菜叶绿体中对山梨醇不通透的3H2O空间（被内膜包围的空间）的情况。1. 苹果酸、天冬氨酸和其他一些二羧酸迅速穿过包膜，导致在叶绿体中积累。这种摄取主要通过与那里存在的二羧酸进行反向交换来进行。2. 二羧酸转运表现出饱和特性，从而可以测定Km和V。3. 所有被转运的二羧酸都作为转运的竞争性抑制剂。4. 根据温度依赖性确定的转运活化能估计为7千卡/摩尔。5. 二羧酸转运速率受光照、反向转运分子和介质pH值的影响。这些变化影响转运速度，而相应的Km值不变。6. 讨论了菠菜叶绿体中二羧酸转运是否涉及不止一种载体。
