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Phase separation in the beta-coil transition of poly-S-carboxyethyl-L-cysteine

✍ Scribed by Hiroshi Maeda; Shoichi Ikeda

Publisher
Wiley (John Wiley & Sons)
Year
1973
Tongue
English
Weight
729 KB
Volume
12
Category
Article
ISSN
0006-3525

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✦ Synopsis

Abstract

The visible phase separation encountered in aqeuous system involving the β‐coil transition is investigated on poly‐S‐carboxyethyl‐L‐cysteine at a constant ionic strength of 0.2 molal. Solubility of the polymer decreases as the average charge density or pH is decreased, indicating that short‐range interactions favor the phase separation. The titration curve of the gel phase (i.e., of the pure β‐structure) is obtained by using the solubility data. Circular dichroism of the solution phase in equilibrium with the gel shows that the β‐structure is present in the solution phase. To isolate the two phases, centrifugal force is applied and it is demonstrated that the polymers in the two phases are in true equilibrium with each other. The effect of total concentration on the solubility of polymer and the degree of neutralization in each phase is interpreted in terms of the poly‐dispersity of the sample.

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