Characterisation of heterogeneous arabinoxylans by direct imaging of individual molecules by atomic force microscopy

Elizabeth L. Adams, Paul A. Kroon, Gary Williamson, Victor J. Morris

Research output: Contribution to journalArticleResearchpeer-review

52 Citations (Scopus)

Abstract

Atomic force microscopy has been used to characterise populations of extracted water-soluble wheat endosperm arabinoxylans. The adsorbed molecules are extended structures with an estimated Kuhn statistical segment length of 128 nm, suggesting that they adopt an ordered helical structure. However, estimates of the molecular weight distribution, coupled with size exclusion data, suggest that, in solution, the polysaccharides behave as semi-flexible coils, with a Kuhn length of 16 nm. These data imply that adsorption of the arabinoxylan structures onto mica promotes formation of the helical structure. Adoption of this ordered structure is fortunate because it has permitted characterisation of branching observed in a small proportion (≈15%) of the population of otherwise linear molecules. The degree of branching has been found to increase with the contour length of the molecules. Degradation of the polysaccharides with xylanase has been used to confirm that both the backbone and branches are based on β-(1→4) linked D-xylopyranosyl residues.

Original languageEnglish
Pages (from-to)771-780
Number of pages10
JournalCarbohydrate Research
Volume338
Issue number8
DOIs
Publication statusPublished - 4 Apr 2003
Externally publishedYes

Keywords

  • Arabinoxylans
  • Atomic force microscopy
  • Helices
  • Kuhn length
  • Pentosans

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