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Sodium counter ion activity of poly-S-carboxyethyl-L-cysteine

✍ Scribed by Hiroshi Maeda

Publisher
Wiley (John Wiley & Sons)
Year
1972
Tongue
English
Weight
574 KB
Volume
11
Category
Article
ISSN
0006-3525

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✦ Synopsis

Counterion activity of poly-8-carboxyethyl-L-cysteine in salefree solutions neutralized to various degrees with sodium hydroxide was determined either directly from the e.m.f measurements of concentration cells formed across a Na-glass electrode, or from the potentiometric titrations at different sodium chloride concentrations assuming the additivity rule.

From e.m.f. measurements, the activity coefficient of counterions was confirmed to display the @-structure random coil transition of the polymer.

For random coil state, both methods gave identical results. Observed values of the activity coefficient was generally smaller than those for other randomly coiled polypeptides. The activity coefficient was found to decrease with the increase of the polymer concentration.

The activity coefficient of counterions foi @-structure was extremely small as compared with that for random coil a t the same degree of neutralization. The activity coefficient obtained from titrations was almost independent of degree of neutralization and iricreased with the increase of the polymer concentration.

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