The identification and characterization of two populations of aggregating proteoglycans of high buoyant density isolated from post-natal human articular cartilages of different ages.
After chromatography on Sepharose CL-2B under associative conditions, high-buoyant-density human articular-cartilage proteoglycans were analysed biochemically and by radioimmunoassay with monoclonal antibodies to a core-protein-related epitope and to keratan sulphate. An examination of proteoglycans from individuals of different ages revealed the presence at 1 year of mainly a single polydisperse population containing chondroitin sulphate (uronic acid) and keratan sulphate. From 4 years onwards a smaller keratan sulphate-rich and chondroitin sulphate-deficient population appears in increasing amounts until 15 years. At the same time the larger population shows a progressive decrease in size from 1 year onward. By 23 years and after the proportion of keratan sulphate in the larger chondroitin sulphate-rich proteoglycan increases. Both adult proteoglycan populations are shown immunologically to aggregate with hyaluronic acid, with the smaller showing a greater degree of interaction. The larger population is richer in serine and glycine, and the smaller population contains more glutamic acid/glutamine, alanine, phenylalanine, lysine and arginine; its protein content is also higher. Whether the larger post-natal population represents a different gene product from the single polydisperse population found in the human fetus, which has a different amino acid composition, remains to be established. The smaller population, which represents approximately one-third the mass of the larger population in the adult, may represent a degradation product of the larger population, in which the hyaluronic acid-binding region and keratan sulphate-rich region are conserved.
Webber
C
C
Joint Diseases Laboratory, Shriners Hospital for Crippled Children, Montreal, Quebec, Canada.
Glant
T T
TT
Roughley
P J
PJ
Poole
A R
AR
D000368:Aged; D000375:Aging; D000596:Amino Acids / Q000032:analysis; D002358:Cartilage, Articular / Q000378:metabolism*; D002850:Chromatography, Gel; D005688:Galactosamine / Q000032:analysis; D005944:Glucosamine / Q000032:analysis; D006801:Humans; D046911:Macromolecular Substances; D008875:Middle Aged; D011509:Proteoglycans / Q000378:metabolism*; D011863:Radioimmunoassay; D014574:Uronic Acids / Q000032:analysis
D000596:Amino Acids; D046911:Macromolecular Substances; D011509:Proteoglycans; D014574:Uronic Acids; D005688:Galactosamine; D005944:Glucosamine