title: An improvement in the bending ability of a hinged trisaccharide with the assistance of a sugar-sugar interaction.
abstract: Hinged di- and trisaccharides incorporating 2,4-diamino-beta-D-xylopyranoside as a hinge unit (Hin) were synthesized. Bridging of the diamino group of Hin by carbonylation or chelation to a metal ion results in a conformational change from (4)C1 to (1)C4, which in turn causes a bending of the oligosaccharides. In this study, the bending abilities of the hinged oligosaccharides were compared, in terms of the reactivities toward carbonylation and chelation. Di- or trisaccharides containing a 6-O-glycosylated mannopyranoside or galactopyranoside at their reducing ends had bending abilities similar to that of the Hin monosaccharide, probably because there were neither attractive nor repulsive interactions between the reducing and nonreducing ends. However, when Hin was attached at O2 of methyl mannopyranoside (Man alphaMe), the bending ability was dependent on the nonreducing sugar and the reaction conditions. Typically, a disaccharide--Hin beta(1,2)Man alphaMe--was difficult to bend under all the tested reaction conditions, and the bent population in the presence of Zn(II) was only 4%. On the other hand, a trisaccharide--Man alpha(1,3)Hin beta(1,2)Man alphaMe--was bent immediately after the addition of Zn(II) or Hg(II), and the bent population reached 75%, much larger than those of all the other hinged trisaccharides ever tested (<40%). This excellent bending ability suggests an attractive interaction between the reducing and nonreducing ends. The extended conformation was recovered by the addition of triethylenetetramine, a metal ion chelator. Reversible, quick, and efficient bending of the hinged trisaccharide was thus achieved.
authors.affiliation: Department of Life Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 B3 Nagatsutacho, Midoriku, Yokohama 226-8501, Japan. hyuasa@bio.titech.ac.jp
authors.forename: Hideya
authors.initials: H
authors.lastname: Yuasa
authors.forename: Takuhiro
authors.initials: T
authors.lastname: Izumi
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Mitsuhashi
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kajihara
authors.forename: Hironobu
authors.initials: H
authors.lastname: Hashimoto
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy / Q000379:methods / Q000592:standards; D019216:Metals, Heavy / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009942:Organometallic Compounds / Q000138:chemical synthesis; D012015:Reference Standards; D014312:Trisaccharides / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D019216:Metals, Heavy; D009942:Organometallic Compounds; D014312:Trisaccharides