The galactosamine residue in mycobacterial arabinogalactan is α-linked.

Wenjie Peng, Lu Zou, Suresh Bhamidi, Michael R McNeil, Todd L Lowary

Alberta Glycomics Centre and Department of Chemistry, The University of Alberta, Edmonton, Alberta T6G 2G2, Canada.

The Journal of organic chemistry 2012 Nov 2

filter terms:

Previous studies have demonstrated that cell wall arabinogalactan from mycobacteria possesses a single galactosamine (GalN) residue. This moiety, which is one of the rare natural occurrences of galactosamine lacking an acetyl group on the nitrogen, has been identified as a pendant substituent attached to a highly branched arabinofuranose residue in the arabinan core. However, the stereochemistry by which the GalN residue is linked to the polysaccharide remains unknown. We report here the synthesis of two tetrasaccharides, 1 and 2, consisting of GalN attached through either an α- or β-linkage to a trisaccharide fragment of mycobacterial arabinan. These molecules represent the first synthetic GalN-containing oligosaccharides, and the preparation of both targets was achieved from a single donor species by modulation of the reaction solvent. Comparison of the NMR spectra of 1 and 2 with those obtained from a sample derived from the natural glycan revealed that the GalN residue in the polysaccharide is attached via an α-linkage.

Citation

Wenjie Peng, Lu Zou, Suresh Bhamidi, Michael R McNeil, Todd L Lowary. The galactosamine residue in mycobacterial arabinogalactan is α-linked. The Journal of organic chemistry. 2012 Nov 2;77(21):9826-32