Diffusion of Rod‐Like Polypeptides in the Liquid Crystalline and Isotropic Phases as Studied by High Field‐Gradient NMR Spectroscopy

Abstract

AbstractIn this lecture the measurements and analyses of the isotropic and anisotropic diffusion coefficients(D) of rod‐like polypeptide such as poly(γ‐L‐glutamate)(PLG) with n‐alkyl side chains, of which the main chain takes the α‐helical conformation, as a function of the main chain length in the thermotropic and lyotropic liquid crystalline phases over a wide range of temperatures from 30 to 80°C by means of pulse high field‐gradient spin echo 1H NMR method have been introduced. In the anisotropic diffusion, the D∥ value in direction parallel to the α‐helical chain axis is found to be much larger than the D⊥ value in direction perpendicular to the α‐helical chain axis. The diffusion process is followed by the Kirkwood theory. Further, it is described that the diffusion in the nematic liquid crystalline phase is much slower than that in the isotropic phase.