The role of link-protein in the structure of cartilage proteoglycan aggregates.
Proteoglycan fractions were prepared from pig laryngeal cartilage. The effect of link-protein on the properties of proteoglycan-hyaluronate aggregates was examined by viscometry and analytical ultracentrifugation. Aggregates containing link-protein were more stable than link-free aggregates at neutral pH, at temperatures up to 50 degrees C and in urea (up to 4.0M). Oligosaccharides of hyaluronate were able to displace proteoglycans from link-free aggregates, but not from the link-stabilized aggregates. Both types of aggregate were observed in the ultracentrifuge, but at the concentration investigated (less than 2 mg/ml) the link-free form was partially dissociated and the proportion aggregated varied with the pH and temperature and required more hyaluronate for saturation than did link-stabilized aggregate. The results showed that link-protein greatly strengthened the binding of proteoglycans to hyaluronate and suggest that under physiological conditions it 'locks' proteoglycans on to the hyaluronate chain.
D000818:Animals; D002352:Carrier Proteins; D002356:Cartilage / Q000032:analysis*; D055598:Chemical Phenomena; D002621:Chemistry; D006820:Hyaluronic Acid; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances; D011509:Proteoglycans; D013552:Swine; D013696:Temperature; D014461:Ultracentrifugation; D014783:Viscosity
D002352:Carrier Proteins; D046911:Macromolecular Substances; D011509:Proteoglycans; D006820:Hyaluronic Acid