Steric Structure of l-Proline Oligopeptides. IV. Proton Magnetic Resonance Studies of l-Proline Oligopeptides

The NMR spectra of t-amyloxycarbonyl-l-proline oligopeptides were measured and compared with those of two poly-l-prolines, I and II. The α-CH resonance peaks of the oligopeptides were observed at sheilding values of 5.2 and 5.4 ppm, values which were in accord with those of the α-CH resonance peaks of the poly-l-prolines I and II, respectively. The behavior of the α-CH peaks was related to the conformation of the l-proline oligopeptides. Moreover, the contribution of the two terminal l-proline residues to the α-CH resonance peaks was discussed.