Determination of Keratan Sulfate and Chondroitin /Dermatan Sulfate Disaccharides during Chick Corneal Development by Electrospray Tandem Mass Spectrometry

Abstract

In cornea, keratan sulfate (KS) and chondroitin/dermatan sulfate (CS/DS) are the two major glycosaminoglycans (GAGs). In this study, electrospray ionization tandem mass spectrometry (ESI-MS/MS) was employed to quantify changes in KS and CS/DS sulfated disaccharides in the developing chick cornea. The concentration of KS monosulfated disaccharide (MSD) Gal-â-1,4-GlcNAc(6S) in embryonic Day 8 (E8) cornea equals that at E20, falls to its lowest level by E10, rises to a second peak by E14, falls to a second low by E18, peaks again by E20, and remains high in adult corneas. A similar concentration profile is observed for KS disulfated disaccharide (DSD) Gal(6S)-â-1,4-GlcNAc(6S), and thus also for total sulfated KS disaccharides. The molar percent of DSD is higher than that of MSD from E8-E18, equivalent at E20, and less than that of MSD in adult corneas. In contrast, total concentration of CS/DS Ddi-4S plus Ddi-6S decreases as development progresses and is lowest in adult corneas. Concentration and molar percent of Ädi-6S is highest at E8, then decreases through development as the concentration and molar percent of Ddi-4S increases from E8 and exceeds that of Ddi-6S after E14. New rapid, direct chemical analysis of extracellular matrix components obtained from sections from embryonic and adult chick corneas reveals heretofore undetected changes in sulfation characteristics of KS and CS/DS disaccharides during corneal development.