Studies in polyelectrolytes. Part 1.—Ionization and optical rotatory behaviour of some polypeptides containing glutamic acid

A series of random copolymers of α-L-glutamic acid and its γ-ethyl ester were synthesized and their behaviour as polyelectrolytes investigated. Measurements of ionization and counter-ion association of these polymers in aqueous dioxan are described and these results are correlated to the α-helix to coil transition. Concomitant measurements of optical rotatory dispersion enables comparison of the predicted and actual transition to be made. From the ionization and association behaviour, a value for the equilibrium constant for the addition of a residue of coil to the end of the α-helix was estimated to be 1.27±0.14.