ISSN:
1573-5001
Keywords:
Oligosaccharide
;
Hydroxyl proton
;
Selective 3D NMR
;
Long-range {1H,13C}J-coupling
;
Metropolis Monte Carlo simulation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary We present a comprehensive strategy for detailed characterization of the solution conformations of oligosaccharides by NMR spectroscopy and force-field calculations. Our experimental strategy generates a number of interglycosidic spatial constraints that is sufficiently large to allow us to determine glycosidic linkage conformations with a precision heretofore unachievable. In addition to the commonly used {1H,1H} NOE contacts between aliphatic protons, our constraints are: (a) homonuclear NOEs of hydroxyl protons in H2O to other protons in the oligosaccharide, (b) heteronuclear {1H,13C} NOEs, (c) isotope effects of O1H/O2H hydroxyl groups on13C chemical shifts, and (d) long-range heteronuclear scalar coupling across glycosidic bonds. We have used this approach to study the trisaccharide sialyl-α(2→6)-lactose in aqueous solution. The experimentally determined geometrical constraints were compared to results obtained from force-field calculations based on Metropolis Monte Carlo simulations. The molecule was found to exist in 2 families of conformers. The preferred conformations of the α(2→6)-linkage of the trisaccharide are best described by an equilibrium of 2 conformers with Φ angles at −60° or 180° and of the 3 staggered rotamers of the Ω angle with a predominantgt conformer. Three intramolecular hydrogen bonds, involving the hydroxyl protons on C8 and C7 of the sialic acid residue and on C3 of the reducing-end glucose residue, contribute significantly to the conformational stability of the trisaccharide in aqueous solution.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01875524
Permalink
