[Changes in biochemical characteristics of collagen and the cartilage water in osteoarthritis].

The stability of collagen molecules and moisture capacity of human normal and osteoarthrotic (OA) cartilage were studied before and after extraction of glycosaminoglycans (GAG) by 4M guanidinum chloride. The content and nature of water were determined by Fisher titration, DSC and analysis of sorbtion-desorbtion processes of water vapour in cartilage. The stability of collagen molecules was determined by the degree of enzymatic hydrolysis: collagenase, pronase and pepsin. It was found that weakening of bonds between main compounds of the cartilage matrix and decrease of GAG quantities in the OA cartilage were accompanied by structural disorganization of the collagen network, which is manifested by breakdowns of intramolecular bonds in telopeptides and intermolecular bonds in the spiral part of collagen molecules, these changes may contribute to increase of total water in OA cartilage. The correlation of free and bound water fractions in cartilage was increased from 5 to 44 in OA cartilage. These results can be used as a criterion of pathological condition of human articular cartilage.