Characterization of chondroitin sulfate-rich proteoglycans from bovine corneal stroma

Abstract

Proteoglycans were extracted from bovine corneal stroma and a chondroitin sulfate-rich fraction amounting to about one third of the corneal proteoglycans was isolated and characterized. The molecular size of the proteoglycans varied but most of the material was partly included in 4% agarose gels. A subfraction (comprising 13% of the proteoglycans) with small molecular sizes had an average molecular weight of 49 000 and an average Stokes' radius of 7·5 nm. Other subfractions were too polydisperse and complex to permit determination of molecular parameters. A large proportion of the small molecular size proteoglycans contains only one chondroitin (or dermatan) sulfate chain bound to a protein core. A small but significant proportion of larger molecular size proteoglycans carries keratan sulfate chains covalently bound to the same protein core as chondroitin and/or dermatan sulfate chains. Oligosaccharides covalently bound to the protein cores were identified. They were rich in mannose, galactose and glucosamine.