Conformational energy calculations and proton nuclear overhauser enhancements reveal a unique conformation for blood group A oligosaccharides

Journal Article · Wed Oct 01 04:00:00 EDT 1986 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00280a010· OSTI ID:6358671

Bush, C A; Yan, Z Y; Rao, B N.N.

The H NMR spectra of a series of blood group A active oligosaccharides containing from four to ten sugar residues have been completely assigned, and quantitative nuclear Overhauser enhancements (NOE) have been measured between protons separated by known distances within the pyranoside ring. The observation of NOE between anomeric protons and those of the aglycon sugar as well as small effects between protons of distant rings suggests that the oligosaccharides have well-defined conformations. Conformational energy calculations were carried out on a trisaccharide, Fuc( -1 2)(GalNAc( -1 3))-GalUS -O-me, which models the nonreducing terminal fragments of the blood group A oligosaccharides. The results of calculations with three different potential energy functions which have been widely used in peptides and carbohydrates gave several minimum energy conformations. In NOE calculations from conformational models, the rotational correlation time was adjusted to fit T1's and intra-ring NOE. Comparison of calculated maps of NOE as a function of glycosidic dihedral angles showed that only a small region of conformational space was consistent with experimental data on a blood group A tetrasaccharide alditol. This conformation occurs at an energy minimum in all three energy calculations. Temperature dependence of the NOE implies that the oligosaccharides adopt single rigid conformations which do not change with temperature.

• Research Organization: Illinois Institute of Technology, Chicago
• OSTI ID: 6358671
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 108:20; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BARYONS
BIOLOGICAL MATERIALS
BLOOD
BODY FLUIDS
CARBOHYDRATES
ELEMENTARY PARTICLES
FERMIONS
HADRONS
MATERIALS
MOLECULAR STRUCTURE
NMR SPECTRA
NUCLEONS
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
PROTONS
SACCHARIDES
SPECTRA