β‐STRUCTURE OF POLYPEPTIDES IN NON‐AQUEOUS SOLUTIONS: II. Side‐Chain Orientation

The specific side‐chain orientations of the phenyl group in the polypeptides poly‐S‐benzyl‐l‐cysteine, poly‐S‐carbobenzoxy‐l‐cysteine and poly‐O‐carbobenzoxy‐l‐serine in the β‐structure have been studied by spectral measurements in solution. All the three polypeptides exhibit aromatic CD bands, indicating the asymmetric placement of the side‐chain phenyl rings when the polypeptide backbone takes up the antiparallel β‐structure. Supporting evidence for this is derived from n.m.r. spectra of the polypeptides, which show up field shift of the phenyl protons due to the stacking of the aromatic rings. Molecular model building studies reveal the stacking of alternate phenyl groups along the polypeptide chain.

β‐STRUCTURE OF POLYPEPTIDES IN NON‐AQUEOUS SOLUTIONS: II. Side‐Chain Orientation Journal Articles