Superstructure in Polypeptide Films as Noted by Small Angle Light Scattering

Films of various synthetic polypeptides were investigated by use of low angle photographic light scattering. Some oriented films of poly-ybenzyl-L-glutamate (PBLG) were prepared by casting them in the presence of a. strong magnetic field. These were also investigated by both light scattering and by wide angle X-ray diffraction. Some light scattering experiments were carried out on 6lms of reconstituted collagen in order to make some comparisons between the synthetic and natural peptides. It was found that, in general, a superstructure exists which can be interpreted as having the character of optically anisotropic rods. Speculation is made regarding the formation of these rod-like aggregates. Some electron electronmicroscopy was done to note the actual presence of these rod or fibrillar-like bundles. It wm found that these anisotropic bodies also exist in the magnetically oriented films but their long axis is found to lie perpendicular to the direction of the field while the molecular axi s lies parallel to the field as noted from X-ray diffraction. No well-defined optical transitions were observed on either compression molded or chloroform cast films of PBLG when measured as a function of temperature.