title: Structure of the O-polysaccharide from the lipopolysaccharide of Providencia alcalifaciens O31 containing an ether of D-mannose with (2R,4R)-2,4-dihydroxypentanoic acid.
abstract: Recently, ether-linked diastereomeric 2,4-dihydroxypentanoic acids have been reported as new components of bacterial glycans [Shashkov, A. S. et al.Nat. Prod. Commun.2008, 3, 1625-1630]. In this work, an ether of (2R,4R)-2,4-dihydroxypentanoic acid (Dhpa) with d-mannose was identified in the O-polysaccharide of Providencia alcalifaciens O31, and the polysaccharide structure was elucidated. Studies by NMR spectroscopy confirmed the ether linkage between O-2 of Dhpa and O-4 of Man, and the absolute configuration of Man was determined after ether cleavage with boron trichloride. In the polysaccharide, Dhpa was found to exist partially in the form of 1,4-lactone. Using sugar and methylation analyses along with (1)H and (13)C NMR spectroscopy, including 2D (1)H,(1)H COSY, TOCSY, ROESY, H-detected (1)H,(13)C HSQC, and gHMBC experiments, the following structure of the tetrasaccharide repeating unit of the polysaccharide was established: [carbohydrate structure: see text]
authors.affiliation: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation. olga.ovchinnikova@gmail.com
authors.forename: Olga G
authors.initials: OG
authors.lastname: Ovchinnikova
authors.forename: Nina A
authors.initials: NA
authors.lastname: Kocharova
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Shashkov
authors.forename: Magdalena
authors.initials: M
authors.lastname: Bialczak-Kokot
authors.forename: Yuriy A
authors.initials: YA
authors.lastname: Knirel
authors.forename: Antoni
authors.initials: A
authors.lastname: Rozalski
mesh_terms: D002240:Carbohydrate Sequence; D008070:Lipopolysaccharides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008358:Mannose / Q000737:chemistry*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010421:Pentanoic Acids / Q000737:chemistry*; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D011532:Providencia / Q000737:chemistry*
chemical_list: D008070:Lipopolysaccharides; D010421:Pentanoic Acids; D011135:Polysaccharides, Bacterial; D008358:Mannose