Structural characterisation of two hexasaccharides and an octasaccharide from chondroitin sulphate C containing the unusual sequence (4-sulpho)-N-acetylgalactosamine β1-4-(2-sulpho)-glucuronic acid β1-3-(6-sulpho)-N-acetylgalactosamine

The structures of two hexasaccharides and an octasaccharide, isolated from shark cartilage chondroitin sulphate C after partial chondroitin ABC lyase digestion, have been elucidated by disaccharide analysis, liquid secondary-ion mass spectrometry, and H-1/C-13 NMR spectroscopy. In the case of the octasaccharide, the order of the internal disaccharide units was deduced from a novel one-dimensional TOCSY/ROESY excitation sculpting experiment [Gradwell M. J., Kogelberg, H. & Frenkiel, T. A. (1997) J. Magn. Reson. 124, 267-270] which incorporates two double-pulsed field-gradient spin-echo sequences. The oligosaccharides each contain the unusual motif GalNAc(4SO(3)(-))beta 1-4GlcA(2SO(3))beta 1-3GalNAc(6SO(3)(-)). From the adjoining sequences in the oligosaccharides, it is apparent that this motif occurs interspersed with typical chondroitin sulphate-C disaccharides, GlcA beta 1-3GalNAc(6SO(3)(-)). Such differentially sulphated domains along the glycosaminoglycan chains are potential sites for specific recognition processes.