Chondroitin sulphate proteoglycans in the vitreous gel of sheep and goat.

In the present study, the amounts and the fine structural characteristics of chondroitin sulphate proteoglycans (CSPGs) present in sheep and goat vitreous gels were determined. The results showed that in both examined species hyaluronan was the predominant glycosaminoglycan (GAG), whereas CSPGs were present in minor amounts. CSPGs were identified as versican and collagen IX with versican being the predominant PG type. Fine structural characterization indicated that the CS chains of versican in both mammalian species were of smaller size than those found in collagen IX. The difference in the sulphation pattern of CS chains between versican and collagen IX was also of particular interest. The results indicated that the predominant disaccharide type in CS side chains of versican and collagen IX from both sheep and goat vitreous gels was the 4-sulphated disaccharide. CS chains of versican were found to be richer in 4-sulphated disaccharide units than those in collagen IX, which also contained a significant proportion of non-sulphated disaccharides. These findings showed that, firstly, the CS content and the hydrodynamic size of the CS chain and, secondly, the sulphation pattern of CS chains from versican and collagen IX in both sheep and goat vitreous gels are PG type-dependent.