Analysis of Cotton-effect distribution of optical rotatory dispersion for polypeptides in solution

From analysis of optical rotatory dispersion in ultra-violet and visible regions (not in far ultra-violet region), true net rotational strength, symmetrical center and apparent width of circular dichroism band were obtained for helical, random and intermediate polypeptides in aqueous solutions or organic solvents. For helical and random poly-L-glutamic acid in aqueous solutions, these characteristic values agree pretty well with the theoretical results calculated from circular dichroism measurements in far ultra-violet region. Helical polypeptides in non-aromatic organic solvents seem to have the similar distribution of Cottoneffects with those for poly-L-glutamic acid, however for helical polypeptides in aromatic solvents, the broader distribution and the red shift of symmetrical center were expected. Also poly-L-alanine in dichloroacetic acid was suggested to have intermediate form by the present analysis.