Ultrastructural Deformation of Collagen

Abstract

Ultrastructure deformation studies of reconstituted and native rat tail tendon collagen revealed that deformation occurs primarily in the non-staining and presumably non-polar proline rich regions for all ages examined. At low deformation (tension and compression) the deformation occurs somewhat more between the as₂ and b₁ and b₂ and C₂ bands than within the rest of the d period. At moderate elongations (greater than 40 %), the deformation becomes localized between the C₂ and d bands, with subfibrils on the order of 3–15 nm being drawn across the openings between the C₂ and d bands. At high elongations (100 % or greater) d period splitting occurs on a regular basis between the C₂ and d bands, along with a retraction of the 64 nm repeat period into 60 nm segments. It is in this deformation region that the effects of molecular slip and the apparent association of the acid mucopolysaccharides can be noted. These results suggest that crosslinking, if increasing as a function of age, does not affect the deformation characteristics of the individual fibrils and that changes with age in mechanical properties should be sought in changes in the fibril size and their interaction with the surrounding matrix.