Bovine tracheal cartilage proteoglycans. Variations in structure and composition with age.

The variation with age in structure and composition of proteoglycans from bovine tracheal cartilage was studied from fetal life to 12 years of age. Cartilage content of proteoglycans as related to collagen was found to increase with age. The extractability of the proteoglycans decreases markedly with age. Extracted proteoglycans were characterized and change during growth and maturation as follows: 1. They contain fewer chondroitin sulfate chains. The chains are of constant size; but at higher ages they are more highly sulfated, primarily with 6-sulfate groups. 2. They contain an increasing number of constant size keratan sulfate chains, while the number of O-linked oligosaccharides (structurally related to the keratan sulfate linkage region to protein) decreases. 3. They become smaller, at least partially, as a result of an increasing proportion of a smaller size proteoglycan. 4. They have a higher protein content. The changes can largely be attributed to an early shift (up to 22 months of age) from a predominating large chondroitin sulfate rich proteoglycan in the youngest cartilage to increasing proportions of a distinct, smaller keratan sulfate rich proteoglycan. During subsequent aging all molecular parameters as well as proportions of subpopulations of proteoglycans remain rather constant.