Biochemical Heterogeneity of the Corneal Glycosaminoglycans

Publisher Website
Google Scholar
Abstract
A procedure has been developed for the extraction and purification of the corneal glycosaminoglycans under mild conditions and without the use of proteolytic enzymes. Nearly 85% of the stromal glycosaminoglycans were solubilized by homogenization of the fresh tissue with water and 0.1 m potassium carbonate at 4°C in a VirTis homogenizer. Proteins not associated with methods the glycosaminoglycans were removed by passing the extracts through SE-Sephadex columns. The keratan sulfates were then separated from the chondroitin sulfates by treatment with ammonium sulfate, and each of the fractions was then chromatographed separately on DEAE-Sephadex. Chemical analyses showed that the two populations of stromal glycosaminoglycans are highly heterogeneous. The four species of chondroitin sulfate differed from one another mainly in sulfate content, with the ratio sulfate/galactosamine varying from 0.43 to 0.89. The principal amino acids in the chondroitin sulfate-peptide molecule were glutamic acid, serine, glycine and aspartic acid. Seven species of keratan sulfate, with ratios of sulfate/glucosamine varying from 0.92 to 1.70, were isolated. Only one of the fractions, representing approximately 16% of the total population, was undersulfated. All the others contained one or more moles of sulfate for each mole of amino sugar. The various keratan sulfate fractions were also heterogeneous with respect to neutral sugar content in that four of them contained approximately equimolar amounts of galactose and glucosamine while in the other three, the ratio of galactose/glucosamine was approximately 1.5. The principal amino acid in all of the keratan sulfate fractions was aspartic acid.

This publication has 0 references indexed in Scilit: