Structure of type I and type III heterotypic collagen fibrils: an X-ray diffraction study

J Struct Biol. 2002 Jan-Feb;137(1-2):15-22. doi: 10.1006/jsbi.2002.4459.

Abstract

The molecular packing arrangement within collagen fibrils has a significant effect on the tensile properties of tissues. To date, most studies have focused on homotypic fibrils composed of type I collagen. This study investigates the packing of type I/III collagen molecules in heterotypic fibrils of colonic submucosa using a combination of X-ray diffraction data, molecular model building, and simulated X-ray diffraction fibre diagrams. A model comprising a 70-nm-diameter D- (approximately 65 nm) axial periodic structure containing type I and type III collagen chains was constructed from amino acid scattering factors organised in a liquid-like lateral packing arrangement simulated using a classical Lennard-Jones potential. The models that gave the most accurate correspondence with diffraction data revealed that the structure of the fibril involves liquid-like lateral packing combined with a constant helical inclination angle for molecules throughout the fibril. Combinations of type I:type III scattering factors in a ratio of 4:1 gave a reasonable correspondence with the meridional diffraction series. The attenuation of the meridional intensities may be explained by a blurring of the electron density profile of the D period caused by nonspecific or random interactions between collagen types I and III in the heterotypic fibril.

MeSH terms

  • Animals
  • Biophysical Phenomena
  • Biophysics
  • Collagen Type I / chemistry*
  • Collagen Type I / ultrastructure
  • Collagen Type III / chemistry*
  • Collagen Type III / ultrastructure
  • Colon / metabolism
  • Fibrillar Collagens / chemistry*
  • Fibrillar Collagens / ultrastructure
  • Intestinal Mucosa / metabolism
  • Models, Molecular
  • Rats
  • Scattering, Radiation
  • X-Ray Diffraction
  • X-Rays

Substances

  • Collagen Type I
  • Collagen Type III
  • Fibrillar Collagens