Potentiometric studies of hydrophobic effect on ion binding of ionic dextran derivatives

✍ Scribed by Kunihiko Gekko; Hajime Noguchi

• Publisher: Wiley (John Wiley & Sons)
• Year: 1975
• Tongue: English
• Weight: 555 KB
• Volume: 14
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1975.360141211

✦ Synopsis

Abstract

In order to clarify the effect of degree of substitution of ionic and hydrophobic group on the polyelectrolytic behavior of polysaccharides, potentiometric titration and activity measurement of counterions were made for carboxymethyldextran (Cm‐dextran) having various degrees of substituted carboxyl group and for carboxymethylbenzyldextran (Cm‐Bzl‐dextran) containing various degrees of substituted benzyl group. From the shape of titration curve, no conformational change was observed for both Cm‐dextran and Cm‐Bzl‐dextran. The p__K__~0~ value of Cm‐dextran was independent of the degree of the degree of substituted carboxy group. However, the p__K__~0~ of Cm‐Bzl‐dextran increased with an increasing degree of substituted benzyl group. The suppression of dissociation of a carboxyl group, caused by the surrounding hydrophobic groups, was discussed mainly in terms of the change of water structure around such groups. From the results of activity measurement for counterions of these dextran derivatives, we proposed the possibility of ion selectivity based on the hydrophobicity.