蛋白质模型化合物PEG对钾离子吸附研究

Studies of Adsorption of Potassium Ion by Polyethlene Glycol as Model Compound of Protein

本文利用Ｋ＋选择电极来研究蛋白质模型化合物聚乙二醇（ＰＥＧ）在水溶液中对Ｋ＋的吸附行为。实验表明：在本体系中Ｋ＋并不完全以游离状态存在，部分Ｋ＋呈吸附缔合状态，并随实验条件而变化。ＰＥＧ对Ｋ＋的吸附同冠醚相似，基本上以８～１１个醚氧吸附缔合一个Ｋ＋。当ＰＥＧ分子量较大时，由于受到空间位阻或形成“冠醚”串时连接部分的需要，相对平均就要１１个醚氧才能吸附缔合一个Ｋ＋。同时Ｋ＋与Ｈ＋间存在着竞争吸附平衡。

In this paper, the behavior of potassium ion adsorpted by polyethlene glycol (PEG) as model compound of protein in water solution was studied by means of ionic selective electrodes.The experimental results show that in system the potassium ion exists not only in free state,but also in adsorbed state. And the existential state is changed with the condition of experiment. It is considered that the adsorption of potassium ion on PEG is similar to crown ether.About 8～11 pieces of ether-oxygen bonds in the PEG can adsorb one potassium ion in aqueous solution. Because of the resistance of space situation or requirement of joined links forming chains of crown ehter, about 11 ether-oxygen bonds are needed to adsorb a potassium ion.And there is adsorbed-association balance between the PEG and potassium ion in solution.