固定化DNA的离子交换特性：聚合物浓度和溶剂性质对碱金属交换的影响

[Ion-exchange properties of immobilized DNA: influence of the polymer concentration and the solvent nature on the exchange of alkali metals].

作者信息

Kuznetsov I A, Kargov S I, Khamizov R Kh, Gorshkov V I

出版信息

Mol Biol (Mosk). 1983 Mar-Apr;17(2):403-9.

Abstract

The method of ion exchange on immobilized DNA, which allows to determine quantitative parameters of ion binding with a high precision, is used for studying of DNA ion selectivity. Insoluble ion exchangers on the DNA basis with the exchange capacity of 0.09 and 0.17 mg-equiv. per 1 g of dry gel are synthesized by means of immobilization of DNA gel in polyacrylamide gel. Constants of ion-exchange equilibrium for the exchanges K+-Na+ and K+-Li+ are determined on these exchangers in water and 50% water-dioxane solution. It is shown that DNA binds selectively only Li+. The selectivity to Li+ increases with the increase of DNA concentration in gel. The specific properties of Li+-DNA in solutions and in the solid state, for example, the impossibility of the B-A transition, are discussed. The selectivity reversal in favor of K+ is observed in water-dioxane solution. The cause of the selectivity reversal and the question of possible participation of cell polyelectrolytes in creation of ion gradients in the living cell are discussed.

摘要

固定化 DNA 上的离子交换方法能够高精度地测定离子结合的定量参数，被用于研究 DNA 的离子选择性。通过将 DNA 凝胶固定在聚丙烯酰胺凝胶中，合成了基于 DNA 的不溶性离子交换剂，其交换容量分别为每 1 克干凝胶 0.09 和 0.17 毫克当量。在这些交换剂上，于水和 50%水 - 二氧六环溶液中测定了 K⁺ - Na⁺ 和 K⁺ - Li⁺ 交换的离子交换平衡常数。结果表明，DNA 仅选择性结合 Li⁺。对 Li⁺ 的选择性随凝胶中 DNA 浓度的增加而增大。讨论了溶液和固态中 Li⁺ - DNA 的特殊性质，例如 B - A 转变的不可能性。在水 - 二氧六环溶液中观察到选择性反转至有利于 K⁺ 的情况。讨论了选择性反转的原因以及细胞聚电解质在活细胞中离子梯度形成过程中可能参与的问题。