Structural characterisation of two hexasaccharides and an octasaccharide from chondroitin sulphate C containing the unusual sequence (4-sulpho)-N-acetylgalactosamine-beta1-4-(2-sulpho)-glucuronic acid-beta1-3-(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 1H/13C 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.es−.rb.ei3.rb)β1−4GlcA(2SO.es−.rb.ei3.rb)β1−3GalNAc(6SO.es−.rb.ei3.rb). From the adjoining sequences in the oligosaccharides, it is apparent that this motif occurs interspersed with typical chondroitin sulphate-C disaccharides, GlcAβ1−3GalNAc(6SO.es−.rb.ei3.rb). Such differentially sulphated domains along the glycosaminoglycan chains are potential sites for specific recognition processes.