Low-angle X-ray diffraction patterns of collagen

Abstract

Measurements have been made of the intensities of up to 25 orders of the low-angle X-ray diffraction patterns of wet and dry collagen fibres from three different sources. From these data Patterson functions have been plotted, and using these curves, and the known results of electron microscopy as guides in making initial assumptions about the electron density distribution in collagen fibres, satisfactory interpretations of the diffraction patterns of wet and dry fibres have been reached. These results show that the conspicuous periodic raised bands seen in electron micrographs of metal-shadowed fibres change in length on wetting the fibres, while the regions between them are but little affected, and it is concluded that these bands are highly disordered regions in dry fibres, becoming more orderly on hydration, while the interbands are always well ordered. Some evidence has also been obtained for the existence of an axial periodicity of about 32$\cdot $8 angstrom.