Synthetic Amphoteric Polypeptide. II. Synthesis and Some Properties of a Reversibly Contractile Amphoteric Polypeptide

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Abstract
1. A reversibly contractile amphoteric polypeptide, copoly-26 : 26 : 1-(l-glutamic acid, l-lysine, Dl-cystine), was synthesised. 2. The foil of this polypeptide contracted at its isoelectric region and extended in both acidic and basic media. This extension and contraction was pH-dependent and fully reversible. 3. The load-elongation relation of the strip of this foil was measured in aqueous media using the load up to about 2,000 times the dry weight per 1 cm. of length of the strip. This relation was linear in this range. 4. The temperature-elongation relation was measured in aqueous media at 20–50°C. From the data it was concluded that, at a given temperature, the internal energy and entropy increased with the elongation of the strip. 5. The change of length of the strip in aqueous media, containing hydrochloric acid, sodium hydroxide, sodium chloride and some other neutral salts individually or in pairs, was measured. Some peculiar and interesting phenomena were observed.