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.
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]
Ovchinnikova
Olga G
OG
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation. olga.ovchinnikova@gmail.com
Kocharova
Nina A
NA
Shashkov
Alexander S
AS
Bialczak-Kokot
Magdalena
M
Knirel
Yuriy A
YA
Rozalski
Antoni
A
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*
D008070:Lipopolysaccharides; D010421:Pentanoic Acids; D011135:Polysaccharides, Bacterial; D008358:Mannose