Acid Dissociation Behavior of 8-Hydroxyquinoline-5-Sulfonic Acid in Molecular Crowding Environment Modeled Using Polyethylene Glycol
Acid Dissociation Behavior of 8-Hydroxyquinoline-5-Sulfonic Acid in Molecular Crowding Environment Modeled Using Polyethylene Glycol
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DOI：
10.1016/j.molliq.2022.119526
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发表时间：
2022-06-07
影响因子：
6
通讯作者：
Nakatani，Kiyoharu
中科院分区：
文献类型：
--
作者：
Miyagawa，Akihisa;Komatsu，Hiroyuki;Nakatani，Kiyoharu
分子拥挤环境中生物分子反应的热力学和动力学与稀溶液中的不同。尽管拥挤溶液中的生物分子反应已经得到了许多研究人员的广泛关注，但对酸解离等基本热力学反应尚不清楚。在此，我们研究了8-羟基喹啉-5-磺酸在分子拥挤中的酸解离热力学行为。用pH滴定法测定了两个酸离解常数Ka1和Ka2在不同相对分子质量的聚乙二醇中的变化。根据渗透压的变化对Kachange进行分析。Ka1和Ka2的温度依赖关系允许我们得到热焓(ΔH)和熵变(ΔS)。ΔHandΔS值表明，解离物种的脱水是由于加入聚乙二醇后水活度降低所致。结果表明，酸在聚乙二醇水溶液中的解离可以用脱水来解释。
The thermodynamics and kinetics of biomolecular reactions in a molecular crowding environment are different from those in dilute solutions. Although biomolecular reactions in crowding solutions have received extensive attention from many researchers, fundamental thermodynamic reactions, such as acid dissociation, are not yet understood. Herein, we investigated the thermodynamic behavior of acid dissociation of 8-hydroxyquinolin-5-sulfonic acid in the molecular crowding. Two acid dissociation constants,Ka1andKa2, in polyethylene glycol (PEG) of different molecular weights were determined by pH titration. TheKachange was analyzed based on the change in osmotic pressure. The temperature dependences ofKa1andKa2allowed us to obtain the enthalpy (ΔH) and entropy changes (ΔS) . The ΔHand ΔSvalues suggest that dehydration of the dissociated species was induced by the decrease in water activity upon the addition of PEG. The results show that the acid dissociation in the PEG solution can be explained by dehydration.