Ling G N, Ochsenfeld M M
J Gen Physiol. 1966 Mar;49(4):819-43. doi: 10.1085/jgp.49.4.819.
A comparison is made between the quantitative predictions of equilibrium ionic distribution in living cells according to the membrane theory (Donnan equilibrium) and according to the association-induction hypothesis. This comparison shows that both theories predict competitive effects of one permeant ion on the equilibrium concentration of another permeant ion; but within the limit of experimental accuracy only the association-induction model predicts quantitatively significant specific competition of one specified ion with the accumulation of another specified ion. The equilibrium distributions of K(+), Rb(+), and Cs(+) ions in frog sartorius muscle were studied and quantitatively significant specific competition was demonstrated; these results favor the association-induction hypothesis (adsorption on cell proteins and protein complexes and partial exclusion from cell water). Based on this model we estimated that at 257deg;C, the apparent association constants for K(+), Rb(+), and Cs(+) ion are 665, 756, and 488 (mole/liter)(-1). We found that the total concentration of adsorption sites (no less than 240 mmole/kg of fresh cells) agrees with the analytically determined concentrations of beta- and gamma-carboxyl groups of muscle cell proteins (260 to 288 mmole/kg).
对根据膜理论（唐南平衡）和缔合-诱导假说得出的活细胞中平衡离子分布的定量预测进行了比较。这种比较表明，两种理论都预测了一种渗透离子对另一种渗透离子平衡浓度的竞争效应；但在实验精度范围内，只有缔合-诱导模型定量预测了一种特定离子与另一种特定离子积累之间显著的特异性竞争。研究了蛙缝匠肌中K(+)、Rb(+)和Cs(+)离子的平衡分布，并证明了显著的特异性竞争；这些结果支持缔合-诱导假说（吸附在细胞蛋白质和蛋白质复合物上，并部分排除在细胞水之外）。基于该模型，我们估计在257℃时，K(+)、Rb(+)和Cs(+)离子的表观缔合常数分别为665、756和488（摩尔/升）(-1)。我们发现吸附位点的总浓度（不少于240毫摩尔/千克新鲜细胞）与肌肉细胞蛋白质中经分析测定的β-和γ-羧基浓度（260至288毫摩尔/千克）相符。
