[On the determination of changes in the large periodic structure of collagen (author's transl)].

Changes in the large periodic structure of collagen were investigated with the aid of synchrotron radiation. Following results were obtained: 1) Macroscopic extension results in elastic deformation of the elements which are determinant for the structure. 2) The increase of the large period is not proportional to the macroscopic stress. 3) The interpretation of these facts requires a mechanical coupling between the structural units. Up to extensions of 4% this coupling is produced by means of a viscoelastic matrix. 4) In all probability the polypeptide helices are deformed in an inhomogeneous mode. The results were set against measurements on human tendon and on artificially crosslinked collagen. The relations between the mechanical behaviour and the change of the large period were compared with the properties of a mathematical model.