Vibrational circular dichroism of polypeptides, V. A study of 3₁₀‐helical‐octapeptides

We have measured vibrational CD spectra in the 3600–1250 cm −1 region of two monodisperse, protected octapeptides, which form right‐handed 3 10 ‐helices in CDC1 3 solution. The spectra are similar in sign pattern to those obtained for right‐handed α‐helices in solution but are smaller in magnitude and, additionally, provide evidence of some line‐shape differences. The delineation of this type of ordered conformation was accomplished by means of 1 H‐nmr. Such a solution structure is consistent with the x‐ray crystal structure of one of these molecules.