Identification of oligomeric domains within dermatan sulfate chains using differential enzymic treatments, derivatization with 2-aminoacridone and capillary electrophoresis

Galactosaminoglycans, i.e. dermatan sulfate (DS) and chondroitin sulfate, a re linear heteropolysaccharides consisting of repeating disaccharide units Of L-iduronic acid (L-IdoA) or D-glucuronic acid (D-GlcA) residues linked t o N-acetyl-galactosamine. High-performance capillary electrophoresis (HPCE or CE) has been successfully used for determining the disaccharide composit ion of glycosaminoglycans. However, only limited information is available o n how to identify oligomeric domains rich in D-GlcA or L-IdoA. The aim of t his study was therefore to develop a rapid and accurate CE procedure by whi ch such oligosaccharides can be determined together with the variously sulf ated disaccharides. Isolated dermatan sulfates of human origin were separat ely digested with chondroitinases ABC, AC and B and the enzymic products we re derivatized with 2-aminoacridone. CE analysis of these products was perf ormed using a phosphate buffer, pH 3.0, and reversed polarity at 30 kV The derivatization enabled their detection with laser-induced fluorescence (LIF ) and UV at 260 nm at much higher sensitivity than the detection of noncler ivatized Delta -saccharides at 232 nm and therefore components undetectable at 232 nm were nicely detected after derivatization. Except for Delta -dis accharides, altogether five distinct oligosaccharides with differences in c harge density were identified. Depending on the lyase that produced these o ligomers, information on the presence Of L-IdoA- or D-GlcA-containing domai ns within the DS chain and the sulfation pattern of these oligomeric domain s was obtained. This CE method could also be useful in studying the functio nal oligomeric domains in galactosamino-glycan chains.