Chair-boat transitions in single polysaccharide molecules observed with force-ramp AFM

Piotr E. Marszalek, Hongbin Li, Andres Oberhauser, Julio M. Fernandez

Research output: Contribution to journalArticle

116 Citations (Scopus)

Abstract

Under a stretching force, the sugar ring of polysaccharide molecules switches from the chair to the boat-like or inverted chair conformation. This conformational change can be observed by stretching single polysaccharide molecules with an atomic force microscope. In those early experiments, the molecules were stretched at a constant rate while the resulting force changed over wide ranges. However, because the rings undergo force-dependent transitions, an experimental arrangement where the force is the free variable introduces an undesirable level of complexity in the results. Here we demonstrate the use of force-ramp atomic force microscopy to capture the conformational changes in single polysaccharide molecules. Force-ramp atomic force microscopy readily captures the ring transitions under conditions where the entropic elasticity of the molecule is separated from its conformational transitions, enabling a quantitative analysis of the data with a simple two-state model. This analysis directly provides the physico-chemical characteristics of the ring transitions such as the width of the energy barrier, the relative energy of the conformers, and their enthalpic elasticity. Our experiments enhance the ability of single-molecule force spectroscopy to make high-resolution measurements of the conformations of single polysaccharide molecules under a stretching force, making an important addition to polysaccharide spectroscopy.

Original languageEnglish (US)
Pages (from-to)4278-4283
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume99
Issue number7
DOIs
StatePublished - Apr 2 2002
Externally publishedYes

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Architectural Accessibility
Ships
Polysaccharides
Atomic Force Microscopy
Elasticity
Spectrum Analysis

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

Chair-boat transitions in single polysaccharide molecules observed with force-ramp AFM. / Marszalek, Piotr E.; Li, Hongbin; Oberhauser, Andres; Fernandez, Julio M.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 99, No. 7, 02.04.2002, p. 4278-4283.

Research output: Contribution to journalArticle

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