title: Extractable proteoglycan from human femoral-head articular cartilage.
abstract: Proteoglycans were prepared from human femoral-head articular cartilage by using either guanidinium hydrochloride or MgCl2 as extractant, followed by density-gradient centrifugation. The proteoglycan subunit had a particle weight of 2.6 x 10(6), with a radius of gyration, RG, of 68.5 nm in 150 mM-NaCl/20 mM-sodium phosphate buffer, pH 7.0. The proteoglycan aggregate had a particle weight of 3.7 x 10(6) (RG 84 nm) for guanidinium hydrochloride extracts and 8.7 x 10(6) (RG 118 nm) for MgCl2 extracts in the same buffer. The addition of excess of high-molecular-weight hyaluronate did not significantly alter the particle size of the aggregate. The small increase in size probably reflects a rapid equilibrium between hyaluronate and proteoglycan monomers, and is not due to proteolytic cleavage producing non-aggregating units. Experiments that support the rapid-interaction hypothesis include analytical ultracentrifugation and column chromatography. This interaction does not appear to be pressure-sensitive at 20 degrees C, but is sensitive to temperature variation near the physiological range.
mesh_terms: D000293:Adolescent; D002358:Cartilage, Articular / Q000032:analysis*; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D005260:Female; D005270:Femur Head / Q000032:analysis; D019791:Guanidine; D006146:Guanidines; D006801:Humans; D006820:Hyaluronic Acid; D007223:Infant; D046911:Macromolecular Substances; D008274:Magnesium; D015636:Magnesium Chloride; D008297:Male; D008875:Middle Aged; D008956:Models, Chemical; D011509:Proteoglycans / Q000302:isolation & purification*; D013696:Temperature
chemical_list: D006146:Guanidines; D046911:Macromolecular Substances; D011509:Proteoglycans; D015636:Magnesium Chloride; D006820:Hyaluronic Acid; D008274:Magnesium; D019791:Guanidine