Nanospring behavior of proteins, nucleic acids and polysaccharides: Single-molecule atomic-force spectroscopy studies

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Date/Time:Monday, 08 Feb 2010 from 4:10 pm to 5:10 pm
Location:Physics, room 5
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Piotr E. Marszalek (Duke University)

Compared to other single-molecule techniques, AFM uses stiff force transducers (cantilevers) and therefore it may apply large stretching forces to molecules. Thus AFM is uniquely capable to determine their high energy conformations that cannot be examined by other techniques such as X-ray crystallography or NMR. In my talk, I will present our AFM studies that are aimed at unraveling the fundamental relationships between structural and mechanical properties of polysaccharides, proteins, and DNA. AFM stretching measurements on polysaccharides reveal that their elasticity frequently deviates from the simple entropic elasticity of other polymers and that it is governed by force-induced conformational transitions within the sugar rings and within the polysaccharide backbone. Investigating the elastic properties of individual proteins such as ankyrin promises to increase the understanding of mechanotransduction, which underlies a sense of touch and hearing. In addition, high resolution AFM measurements of mechanical unfolding and refolding reactions of ankyrin and other repeat proteins, which exhibit unusually strong folding forces, can contribute to elucidating the mechanism of protein folding in general. My DNA research is aimed at exploiting AFM for development of new ultra-sensitive assays for detecting and examining DNA damage, and to increase our understanding of DNA damage and repair processes. This research, in addition to its basic science aspects may lay a foundation for the future use of AFM in the nanoscale DNA diagnostics.