Methyl beta-allolactoside [methyl beta-D-galactopyranosyl-(1-->6)-beta-D-glucopyranoside] monohydrate.
Methyl beta-allolactoside [methyl beta-D-galactopyranosyl-(1-->6)-beta-D-glucopyranoside], (II), was crystallized from water as a monohydrate, C(13)H(24)O(11).H(2)O. The betaGalp and betaGlcp residues in (II) assume distorted (4)C(1) chair conformations, with the former more distorted than the latter. Linkage conformation is characterized by phi' (C2(Gal)-C1(Gal)-O1(Gal)-C6(Glc)), psi' (C1(Gal)-O1(Gal)-C6(Glc)-C5(Glc)) and omega (C4(Glc)-C5(Glc)-C6(Glc)-O1(Gal)) torsion angles of 172.9 (2), -117.9 (3) and -176.2 (2) degrees , respectively. The psi' and omega values differ significantly from those found in the crystal structure of beta-gentiobiose, (III) [Rohrer et al. (1980). Acta Cryst. B36, 650-654]. Structural comparisons of (II) with related disaccharides bound to a mutant beta-galactosidase reveal significant differences in hydroxymethyl conformation and in the degree of ring distortion of the betaGlcp residue. Structural comparisons of (II) with a DFT-optimized structure, (II(C)), suggest a link between hydrogen bonding, pyranosyl ring deformation and linkage conformation.
Klepach
Thomas E
TE
Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556-5670, USA.
Reed
Meredith
M
Noll
Bruce C
BC
Oliver
Allen G
AG
Serianni
Anthony S
AS
D002236:Carbohydrate Conformation; D018360:Crystallography, X-Ray; D004187:Disaccharides / Q000737:chemistry*; D006860:Hydrogen Bonding; D008759:Methylglycosides / Q000737:chemistry*; D008958:Models, Molecular
C546043:(methyl beta-D-galactopyranosyl-(1-6)-beta-D-glucopyranoside) monohydrate; D004187:Disaccharides; D008759:Methylglycosides; C034207:methyl lactoside