Molecular characteristics of soluble arthritic collagens.

The molecular characteristics of acid-soluble collagen prepared from animals rendered adjuvant arthritis and matched controls have been thoroughly investigated. The arthritic process was induced in rats by the injection of paraffin oil containing the suspension of heat-killed Mycobacterium tuberculosis at the dorsum of the tail root. In comparison to the normal, the arthritic collagens consistently demonstrated increased solubility of reconstituted fibrils and marked decrease in intrinsic viscosity. Digestion of arthritic collagens with various proteolytic enzymes showed an increased susceptibility over normal collagens. Electrophoresis on SDS-polyacrylamide gels revealed a marked decrease in the concentration of beta-components of arthritic collagens and appreciable increase in the ratio of alpha to beta subunit component. The data clearly indicate that the arthritic collagens are very poor in polymerization due to the impairment of intra and inter-molecular interactions. These changes could explain in part, the altered response of the connective tissues to inflammation and arthritis.