Intermolecular association of tetra‐(γ‐benzyl‐L‐glutamate)s in ethylene dichloride solutions

Light scattering from ethylene dichloride solutions of tetra‐(γ‐benzyl‐L‐glutamate)s has been measured and their association in solution is examined. One of the peptides is monodisperse o‐nitrophenylthio‐tetra‐(γ‐benzyl‐L‐glutamate) ethylamide prepared by a stepwise condensation method, and the other is low‐molecular‐weight poly(γ‐benzyl‐L‐glutamate) prepared by the N‐carboxyanhydride method with n‐hexilamine initiation at [A]/[I] = 4 and factionated by dosslution in formic acid. Concentration‐dependent association of both peptides occurs noncooperatively, without giving critical micelle concentrations. The aggregate size is small: about 23 for the former tetrapeptide and about 7 for the latter polypeptide. While angular dissymmetry is close to unity, light scattering shows anomalous angular dependence, the intensity being symmetrically low with respect to the scattering angle of 90°. The observed angular dependence is interpreted in terms of the effect of optical anisotropy of peptide units. Formation of the anisotropic phase in concentrated solutions of these peptides is also examined briefy.

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