title: 9-O-Sulfation on alpha-NeuAc-(2-->8)-NeuAc and inter-residue lactonization.
abstract: Treatment of alpha-NeuAc-(2-->8)-NeuAc (1) with SO3-pyridine (4 equiv) in DMF resulted in selective 9-O-sulfation on the nonreducing end residue and the formation of an inter-residual delta-lactone. The lactonization could result from the C-2 carboxylic acid of the nonreducing residue condensing with the hydroxyl group or/and sulfated group at C-9 of the reducing residue to form a six-membered ring between two adjacent sialic acid residues. When alpha-NeuAc-(2-->9)-NeuAc (5) was used as a sulfation substrate, only 9-O-sulfation on the nonreducing end residue was observed. According to capillary electrophoresis (CE) analysis, 9-O-sulfation on the disialic acid is a fast reaction, while sulfation on other hydroxyl groups is insignificant under the conditions used.
authors.affiliation: Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan.
authors.forename: An-Tai
authors.initials: AT
authors.lastname: Wu
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Yu
authors.forename: Chien-Tai
authors.initials: CT
authors.lastname: Ren
authors.forename: Wei
authors.initials: W
authors.lastname: Zou
authors.forename: Shih-Hsiung
authors.initials: SH
authors.lastname: Wu
mesh_terms: D004187:Disaccharides / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D015394:Molecular Structure; D012794:Sialic Acids / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry*
chemical_list: D004187:Disaccharides; D007783:Lactones; C503496:NeuAc-2-8-NeuAc; D012794:Sialic Acids; D013431:Sulfates