Weigl J
Botanisches Institut der Technischen Hochschule Darmstadt, Darmstadt, Deutschland.
Planta. 1967 Dec;75(4):327-42. doi: 10.1007/BF00387356.
Influx and efflux of anions in leaves of Elodea canadensis were investigated. A major component of phosphate efflux was found to be a function of the external phosphate concentration in accord with saturation kinetics, i.e. it was found to be proportional to phosphate influx. This suggests that the transport structures which mediate ion transport in plant membranes are mobile and can work in both directions (Fig. 7C). The higher the external concentration the more bound ions (A b (-) , Fig. 7C) are exchanged for external ions (A a (-) ) instead of being transported back to the inside of the membrane. Thus it was demonstrated that ion transport in plants is mediated by carriers or transportases. The action of the carriers is supported by ATP or another "energy-rich" compound which is regenerated by ATP; ATP may be supplied by the mitochondria or/and chloroplasts. In line with these findings some transport phenomena exhibited features of coenzyme kinetics.Magnitude and molecular nature of the carrier motion are unknown. There is no evidence for rotating or shuttling monovalent carriers. The carriers may be polyvalent and may be part of bigger structural units within the membrane. Nevertheless, these experimental observations are rather consistent with the idea that plant membranes contain tertiary or quarternary formed proteins or lipoproteins than with the conventional lipid bilayer models of cell membranes.
对加拿大伊乐藻叶片中阴离子的流入和流出进行了研究。发现磷酸盐流出的一个主要成分是外部磷酸盐浓度的函数，符合饱和动力学，即发现它与磷酸盐流入成正比。这表明介导植物膜中离子运输的转运结构是可移动的，并且可以双向工作（图7C）。外部浓度越高，就有越多的结合离子（Ab(-)，图7C）被外部离子（Aa(-)）交换，而不是被运回膜内。因此证明了植物中的离子运输是由载体或转运酶介导的。载体的作用由ATP或另一种由ATP再生的“富含能量”的化合物支持；ATP可能由线粒体或/和叶绿体提供。与这些发现一致，一些运输现象表现出辅酶动力学的特征。载体运动的幅度和分子性质尚不清楚。没有证据表明存在旋转或穿梭的单价载体。载体可能是多价的，并且可能是膜内更大结构单元的一部分。然而，这些实验观察结果与植物膜含有三级或四级形成的蛋白质或脂蛋白的观点相当一致，而不是与传统的细胞膜脂质双层模型一致。
