根系对钙的吸收动力学。

The kinetics of calcium uptake by roots.

机构信息

Grasslands Division, D.S.I.R., Private Bag, Palmerston North, New Zealand.

出版信息

Planta. 1973 Jun;112(2):159-67. doi: 10.1007/BF00388586.

Abstract

The time course of the uptake of labelled calcium by roots of Hordeum vulgare L., Trifolium subterraneum L., and Phaseolus aureus Roxb. was found to have two distinct phases: an initial rapid adsorption phase of about 1 h duration (Phase I) and a slower accumulation which proceeded at a constant rate for at least 12 h (Phase II). Ions taken up by the mechanism of Phase I, but not Phase II, could be removed by rinsing the roots in cold solutions of unlabelled CaCl2 or KCl.The concentration dependence of calcium uptake by barley roots over the range 0.001 to 10.0 mN was analysed with the aid of Hofstee plots. Phase I consisted of two Donnan adsorption processes. The half-saturation concentrations were 0.065 mN and 0.002 mN and the respective capacities were 1.56 and 0.36 μeq g(-1) (fresh weight). Phase II displayed Michaelis-Menten kinetics for a single mechanism with a Km=0.077 mN and V max=0.15 μeq g(-1) (fresh weight) h(-1).

摘要

大麦（Hordeum vulgare L.）、三叶草（Trifolium subterraneum L.）和菜豆（Phaseolus aureus Roxb.）根对标记钙的摄取过程被发现具有两个明显的阶段：持续约 1 小时的初始快速吸附阶段（I 期）和至少 12 小时以恒定速率进行的较慢积累阶段（II 期）。通过 I 期但不是 II 期机制摄取的离子可以通过在冷的未标记 CaCl2 或 KCl 溶液中冲洗根系来去除。借助 Hofstee 图分析大麦根系在 0.001 至 10.0 mN 范围内对钙摄取的浓度依赖性。I 期由两个 Donnan 吸附过程组成。半饱和浓度分别为 0.065 mN 和 0.002 mN，相应的容量分别为 1.56 和 0.36 μeq g-1（鲜重）。II 期显示出单一机制的米氏-门坦动力学，Km=0.077 mN 和 V max=0.15 μeq g-1（鲜重）h-1。