Preparation of the Partially Methylated Alditol Acetates Derived from CS Tetrasaccharides Containing Galactose for the Gas Chromatography/Mass Spectrometry Analysis.

Chondroitin sulfate (CS), a member of the glycosaminoglycan (GAG) family of carbohydrates, is composed of linear, sulfated repeating disaccharide sequences of N-acetyl-D-galactosamine (GalNAc) and glucuronic acid (GlcA). Recently, a keratan sulfate (KS) disaccharide [GlcNAc6S(β1-3)Galactose(β1-]-branched CS-E was identified from the clam species M. chinensis. This protocol details a methodology to analyze the glycosidic linkages of galactose in KS disaccharide-branched CS by GC-MS analysis. A complementary method for the identification and characterization of KS-branched CS in M. chinensis can be found in Higashi et al. (2016).