Methyl beta-D-galactopyranosyl-(1-->4)-beta-D-allopyranoside tetrahydrate.
The title compound, C(13)H(24)O(11).4H(2)O, (I), crystallized from water, has an internal glycosidic linkage conformation having phi' (O5(Gal)-C1(Gal)-O1(Gal)-C4(All)) = -96.40 (12) degrees and psi' (C1(Gal)-O1(Gal)-C4(All)-C5(All)) = -160.93 (10) degrees , where ring-atom numbering conforms to the convention in which C1 denotes the anomeric C atom, C5 the ring atom bearing the exocyclic hydroxymethyl group, and C6 the exocyclic hydroxymethyl (CH(2)OH) C atom in the betaGalp and betaAllp residues. Internal linkage conformations in the crystal structures of the structurally related disaccharides methyl beta-lactoside [methyl beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranoside] methanol solvate [Stenutz, Shang & Serianni (1999). Acta Cryst. C55, 1719-1721], (II), and methyl beta-cellobioside [methyl beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranoside] methanol solvate [Ham & Williams (1970). Acta Cryst. B26, 1373-1383], (III), are characterized by phi' = -88.4 (2) degrees and psi' = -161.3 (2) degrees , and phi' = -91.1 degrees and psi' = -160.7 degrees , respectively. Inter-residue hydrogen bonding is observed between O3(Glc) and O5(Gal/Glc) in the crystal structures of (II) and (III), suggesting a role in determining their preferred linkage conformations. An analogous inter-residue hydrogen bond does not exist in (I) due to the axial orientation of O3(All), yet its internal linkage conformation is very similar to those of (II) and (III).
Zhang
Wenhui
W
Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556-5670, USA.
Oliver
Allen G
AG
Serianni
Anthony S
AS
D018360:Crystallography, X-Ray; D006601:Hexoses / Q000737:chemistry*; D006860:Hydrogen Bonding; D008745:Methylation; D008958:Models, Molecular; D008968:Molecular Conformation; D014867:Water / Q000737:chemistry*
D006601:Hexoses; D014867:Water