Constitutional variations of acidic glycosaminoglycans in normal and arthritic bovine articular cartilage proteoglycans at different ages.

Proteoglycans extracted from normal and arthritic bovine articular cartilage of various ages were fractionated and purified under associative and dissociative conditions. After proteolytic digestion, the composition of the acidic glycosaminoglycans (AGAG) in the proteoglycans was determined enzymatically by digestion with chondroitinase-AC II, chondroitinase-ABC, Streptomyces, hyaluronidase and keratanase. Under both associative and dissociative conditions, uniform distribution of chondroitin sulfate (CS) isomers from proteoglycans of different ages was observed: With increasing age, the relative proportion of 4-sulfated disaccharide units in total AGAG decreased, whereas that of 6-sulfated disaccharide units increased. The relative proportion of 4-sulfated disaccharide units in total CS and the ratio of 4-sulfated disaccharide units to 6-sulfated disaccharide units were greater in arthritic cartilages than in normal cartilages of the same ages. At all three ages studied, the relative proportion of 4-sulfated disaccharide units in sequential fractions increased with the decrease of cesium chloride (CsC1) density, as the proportion of 6-sulfated disaccharide units decreased. The relative proportions of hyaluronic acid (HA) and keratan sulfate (KS) increased with age. The AGAG components of cartilage proteoglycans were distributed with a certain regularity in the fractions of CsCl density gradients, but underwent changes with increasing age and in arthritic process.