A novel pentasaccharide sequence GlcA(3-sulfate)(beta 1-3)GalNAc(4-sulfate)(beta 1-4)(Fuc alpha 1-3)GlcA(beta 1-3)GalNAc(4-sulfate) in the oligosaccharides isolated from King Crab cartilage chondroitin sulfate K and its differential susceptibility to chondroitinases and hyaluronidase

Novel sulfated tetrasaccharide structures containing 3-O-sulfated GlcA were isolated recently from king crab cartilage chondroitin sulfate K [Sugahara, K., Tanaka, Y., Yamada, S., Seno, N., Kitagawa, H., Haslam, S. M., Morris, H. R., & Dell, A. (1996) J. Biol. Chem. 271, 26745-26754]. In this study, we prepared a series of oligosaccharides from the same source after exhaustive digestion with testicular hyaluronidase and determined the structures of a pentasaccharide, two hexasaccharides, and two heptasaccharides by means of fast atom bombardment mass spectrometry and 500-MHz H-1-NMR spectroscopy. All the oligosaccharides had the following hitherto unreported structures including a novel glucuronate 3-O-sulfate: GlcA(3S)(beta 1-3)GalNAc(4S)(beta 1-4)GlcA(3S)(beta 1-3)GalNAc(4S)(beta 1-4)GlcA(beta 1-3)GalNAc(4S), GlcA(3S)(beta 1-3)GalNAc(4S)(beta 1-4)GlcA(3S)(beta 1-3)GalNAc(4S)(beta 1-4)GlcA(3S)(beta 1-3)GalNAc(4S), GlcA(3S)(beta 1-3)GalNAc(4S)(beta 1-4)(Fuc alpha 1-3) GlcA(beta 1-3)GalNAc(4S), GlcA(3S)(beta 1-3)GalNAc(4S)(beta 1-4)(Fuc alpha 1-3)GlcA(beta 1-4)GlcA(beta 1-3)GalNAc(4S), and GlcA(3S)(beta 1-3)GalNAc(4S)(beta 1-4)GlcA(3S)(beta 1-3)GalNAc(4S)(beta 1-4)(Fuc alpha 1-3)GlcA(beta 1-3)GalNAc(4S), where 3S or 4S represent 3-O- or 4-O-sulfate, respectively. Furthermore, the three latter structures contained a novel combination of both 3-O-sulfated and 3-O-fucosylated GlcA residues. The pentasaccharide with 3-O-fucosylated GlcA at the internal position remained totally resistant to chondroitinase AC-II, whereas it was degraded by chondroitinase ABC into a disaccharide unit containing GlcA(3S) derived from the nonreducing side and a trisaccharide unit containing fucose from the reducing side.