PHONON-DISPERSION IN POLY(ALPHA-AMINOISOBUTYRIC ACID)

The present work is a study of phonons and their dispersion in poly(al pha-aminoisobutyric acid) (PAIB), which is an example of a poly(amino acid) having a 3(10) helical conformation. PAIB has been used as a mod el to carry out conformational studies on proteins and polypeptides. D ispersion curves show two interesting opposite features: (1) a tendenc y of some curves to crowd or close in near delta = psi,which is indica tive of coupling between various modes, and (2) a divergence of some d ispersion curves belonging to species of the same symmetry. The specif ic heat is obtained from the dispersion curves via the density of stat es.