Crystal structure of methyl alpha-L-rhamnopyranosyl-(1 -> 2)-alpha-L-rhamnopyranoside monohydrate

• The title compound, C13H24O9 center dot H2O, a structural model for part of bacterial O-antigen polysaccharides from Shigella flexneri and Escherichia coli, crystallizes with four independent disaccharide molecules and four water molecules in the asymmetric unit. The conformation at the glycosidic linkage joining the two rhamnosyl residues is described by the torsion angles phi(H) of 39, 30, 37 and 37 degrees, and psi(H) of -32, -35, -31 and -32 degrees, which are the major conformation region known to be populated in an aqueous solution. The hexopyranose rings have the C-1(4) chair conformation. In the crystal, the disaccharide and water molecules are associated through O-H center dot center dot center dot O hydrogen bonds, forming a layer parallel to the bc plane. The layers stack along the a axis via hydrophobic interactions between the methyl groups.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

crystal structure

carbohydrates

disaccharide

conformation

packing

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