X-ray diffraction studies of a silkmoth chorion

High- and low-angle diffraction studies have been performed on mature chorion (eggshell) of the silkmoth, Antheraea polyphemus. The results confirm the prevalence of β-sheet structure, previously suggested by predictions based on known primary structure and by results of laser Raman spectroscopy. The patterns obtained with different irradiation geometries suggest that a significant proportion of β-sheets are stacked and oriented with respect to the chorion surface and the ultrastructurally evident fibrillar components. Strong similarities are evident with the organization of β-sheets in chicken scale keratin.