Structural studies of octasaccharides derived from the low-sulfated repeating disaccharide region and octasaccharide serines derived from the proteinlinkage region of porcine intestinal heparin

Four octasaccharide serines and three octasaccharides were isolated after h eparinase treatment of porcine intestinal heparin. Their structures were ch aracterized by enzymatic digestion in conjunction with HPLC and 500 MHz H-1 NMR spectroscopy. Three of the four octasaccharide serines were structural ly identical with those isolated previously, whereas one has the unreported structure Delta HexA(2-sulfate)alpha 1-4GlcN(N-sulfate)alpha 1-4GlcA beta 1-4G1cNAc alpha 1-4GlcA beta 1-3Gal beta 1-3Gal beta 1-4Xyl beta 1-O-Ser (D elta HexA, GlcN, IdceA, and GlcA represent 4-deoxy-alpha-L-threo-hex-4-enep yranosyluronic acid, D-glucosamine, L-iduronic acid, and D-glucuronic acid, respectively). The other three octasaccharides were isolated for the first time as discrete structures and shared the common core hexasulfated sequen ce Delta HexA(2-sulfate)alpha 1-4GlcN(N-sulfate)alpha 1-4IdceA alpha 1-4Glc NAc alpha 1-4GlcA beta 1-4GlcN(N-sulfate)alpha 1-4IdceA(2-sulfate)alpha 1-4 GlcN(N,6-disulfate) with one or two additional sulfate groups. The octasacc harides which were derived from the low-sulfated repeating disaccharide reg ion of heparin contained the common trisaccharide sequence -4IdceA alpha 1- 4GlcNAc alpha 1-4GlcA beta 1- [Yamada, S., Yamane, Y., Tsuda, H., Yoshida, K., and Sugahara, K. (1998) J. Biol, Chem. 273, 1863-1871], suggesting the programmed biosynthesis of heparin. These octasaccharides are the largest o ligosaccharides isolated so far from the low-sulfated irregular region of h eparin. Since oligosaccharides larger than a pentasaccharide appear to pote ntially exhibit binding activities toward growth factors or other functiona l proteins, they will be useful for investigating the structural requiremen t for molecular interactions between heparin and/or heparan sulfate and bio logically active proteins. During the course of the present structural stud ies, we evaluated the NMR data accumulated thus far on heparin oligosacchar ides and found several interesting rules on chemical shifts of proton signa ls affected by the neighboring sugar residues and their sulfation, which wi ll be in turn useful for determining structures of unknown heparin and/or h eparan sulfate oligosaccharides based on the proton resonances.