Insights into stereochemical features of sulphated carbohydrates: X-ray crystallographic and modelling investigations

Abstract

The three-dimensional structures of the 2-, 3-, 4- and 6-monosulphates of methyl alpha-D-galactopyranoside have been determined by X-ray crystallography; the first two as the sodium salt, the third as both the sodium and potassium salts, and the fourth as a potassium salt. These represent the principal sulphated monomers of the carrageenan polysaccharides. The results extend our knowledge of the stereochemical features, such as ring conformation, sulphate geometry, hydrogen bonding and cation co-ordination, which characterize sulphated monosaccharides. The stereochemical data have been used to derive a mean geometry of the O-sulphate group and a set of force constants for use in molecular mechanics calculations on sulphated monosaccharides. These may be used in an extrapolation of the populations of stable conformers of related oligo- and polysaccharides.

Conformational Studies on Five Octasaccharides Isolated from Chondroitin Sulfate Using NMR Spectroscopy and Molecular Modeling

“…In a first approximation, they can be described by the ( , ψ) potential energy maps of the disaccharide subunits. Taking into account this assumption, adiabatic maps were computed for all of the disaccharides constituting the five octasaccharides ∆C-A-D-C, ∆A-A-D-C, ∆A-A-D-A, ∆C-A-D-A, and ∆C-C-C-C. A set of energy parameters characteristic of sulfate groups was added to the force field, making it suitable for the molecular modeling of sulfated carbohydrates (26). The three terminal oxygen atoms in sulfate groups were generated as equivalent, so C x -O x -S-O S was left as corresponding to any staggered conformation.…”

mm3 Potential energy surfaces of α-3-linked l-fucobiose and fucotriose and their sulfated counterparts

“…MM3 MM3 parameters for the sulfate group were taken from Lamba et al, 22 and a dielectric constant of 3.0 was used. In that model, the charge on the sulfate groups is emulated by S-O bond dipoles, with no cations added.…”

Theoretical study of structure and properties of hexuronic acid and d-glucosamine structural units of glycosaminoglycans

“…2 and 3 together with the atom-numbering scheme. The results of this study are compared with previous theoretical [13][14][15] and experimental [15][16][17][18] data and discussed with the present theories of action of these drugs.…”

“…Computed geometry of the parent saccharides can be compared with published X-ray data of simpler sulfated monosaccharides [16][17][18]. Lamda et al determined crystal and molecular structure of sodium salts of several sulfated galactopyranoses and glucopyranoses [16,17].…”

“…Lamda et al determined crystal and molecular structure of sodium salts of several sulfated galactopyranoses and glucopyranoses [16,17]. The sulphate group is essentially tetrahedral with O-S-O angles ranging from 100.6 to 115.5°.…”