Abstract
A structure is proposed to explain the X-ray diffraction pattern of a naturally occurring cross-β fibrous protein. The well-oriented fibres contain ribbon-like micelles about 25 Å thick with their longest dimension parallel to the fibre axis. The ribbons are packed face to face with a variable interfacial separation around a mean of 15 ± 4 Å. The inner structure of the ribbons is basically that of the Tussah silk model as described by Marsh, Corey & Pauling (1955), but in the cross-β conformation the extended parts of the polypeptide chains run at right angles to the fibre axis. In the protein studied these extended parts are linked together by short “bend” regions to form continuous folded polypeptide chains which lie in planes normal to the surface of the ribbon-like micelles and parallel to their long axis.
Published Version
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