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Intermolecular association of tetra‐(γ‐benzyl‐ L ‐glutamate)s in ethylene dichloride solutions
Author(s) -
Imae Toyoko,
Ikeda Shoichi
Publication year - 1985
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360240401
Subject(s) - chemistry , tetra , dispersity , formic acid , condensation , glutamate receptor , ethylene , tetrapeptide , intermolecular force , scattering , crystallography , peptide , polymer chemistry , organic chemistry , medicinal chemistry , molecule , optics , catalysis , biochemistry , physics , receptor , thermodynamics
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.