[Proteoglycans of human articular cartilage normally and in age-related degenerative changes]

Content of proteoglycans (PG) was decreased in human joint cartilage under degenerative conditions. This decrease occurred mainly due to the PG tightly bound with collagen but not of their monomers as shown by a stepwise extraction of the PG fractions. Fraction of the PG aggregates, not bound with collagen, was relatively increased in degeneratively impaired cartilage; this appears to occur as a result of impairment in reaction of the PG molecules with collagen matrix.