Acetan is an anionic bacterial polysaccharide. The chemical repeat unit consists of a cellobiose unit solubilised by attachment of a charged pentasaccharide sidechain to one of the glucose residues. The repeat unit contains two sites of acetylation. 1H and 13C NMR studies, coupled with both basic-methylation and mild-methylation studies, have shown that acetylation occurs at C6 on the (1,2)D-Man and the (1,34)D-Glc residues. A variety of techniques including NMR, optical rotation, circular dichroism and DSC show evidence for a thermoreversible conformational order (helix)-disorder (coil) transition for acetan in aqueous solution. The studies suggest that acetylation of the backbone does not prevent helix formation.
NMR, conformation, structure, polysaccharide, acidic, methylation, extracellular, O-acetyl, acetan, localisation, A. xylinum polysaccharide, DSC, optical otation, circular dichroism
NCBI PubMed ID: 8910054Journal NLM ID: 7909578Publisher: Butterworth-Heinemann
Institutions: Department of Food Science and Technology, Cranfield University, Silsoe College, Silsoe, Bedford MK45 4DT, UK, IFR Institute of Food Research, Norwich Laboratory, Norwich Research Park, Colney, Norwich, UK
Methods: 13C NMR, 1H NMR, methylation, differential scanning calorimetry (DSC), optical rotation measurement, CD
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