Nature Biotechnology
19, 258 - 262 (2001)
doi:10.1038/85712
Fingerprinting polysaccharides with single-molecule atomic force microscopyPiotr E. Marszalek, Hongbin Li
& Julio M. Fernandez
Department of Physiology and Biophysics, Mayo Foundation, Rochester, MN 55905.
Correspondence should be addressed to Julio M. Fernandez Fernandez.julio@mayo.edu or Piotr E. Marszalek Marszalek.piotr@mayo.eduWe report the use of an atomic force microscopy (AFM)-based force spectroscopy technique to identify, at the single-molecule level, the components of mixtures of polysaccharides. Previously, we showed that the elasticity of certain types of polysaccharides is governed by force-induced conformational transitions of the pyranose ring. These transitions produce atomic fingerprints in the force−extension spectrum that are characteristic of the ground-energy conformation of the pyranose ring and the type of glycosidic linkages. Using this approach we find that commercially available agarose and  -carrageenan contain molecules that, when stretched in an atomic force microscope, produce a force spectrum characteristic of  -(1 4) d-glucans. We have identified these molecules as amylopectin or floridean starch, a storage polysaccharide in algae. Our methodology can identify individual polysaccharide molecules in solution, which is not possible by any other spectroscopic technique, and therefore is an important addition to the arsenal of analytical techniques used in carbohydrate research.
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