Concentration Dependence of the Conversion between the Intermolecular β-Structure and the Disordered State of Poly(S-carboxymethyl-l-cysteine) in Aqueous Solutions

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Abstract
The effects of polymer concentration on the reversible conversion between the intermolecular β-structure and the disordered state of poly(S-carboxymethyl-L-cysteine) were examined by means of circular dichroism at constant pHs in 20 mM NaClO4 solutions. The data were tentatively analyzed based on an assumed all-or-none model. A value of −1.1 kJ (−250 cal) per mole of residues was obtained for the standard free energy of association. It was suggested that the obtained results depended significantly on the molecular weight distribution of the used samples.