N-substituted poly(α-amino acids). 2. Conformational properties of poly(γ-ethyl N-methyl-L-glutamate) in various solvent mixtures

The conformational properties of poly(γ-ethyl N-methyl-L-glutamate) have been investigated under various experimental conditions, using NMR and CD spectroscopy. It was found that in a number of solvents including water, trifluoroethanol, and trifluoroacetic acid, poly(γ-ethyl N-methyl-L-glutamate) assumes an extremely stable helical conformation, whose chiroptical properties are very close to those of poly(N-methyl-L-alanine). Computer-simulated model studies have been carried out assuming the and dihedral angles of the poIy(N-methyl-L-alanine) helix to be 30 and 240°, respectively, according to 1966 convention. The structure reveals a hydrophobic groove which in aqueous solution could be partly responsible for the intrinsic conformational stability. Side chains are well separated from one another in the structure, and interactions among them appear unlikely. © 1979, American Chemical Society. All rights reserved.