Event
Bioengineering Seminar Series: Joonil Seog
Friday, December 4, 2009
11:00 a.m.
Room 2108, Chemical and Nuclear Engineering Bldg.
Professor Adam Hsieh
hsieh@umd.edu
Understanding Biological Mechanisms Using High Resolution Force Spectroscopy
Presented by Joonil Seog
Assistant Professor, Fischell Department of Bioengineering and Department of Materials Science and Engineering
University of Maryland
Atomic Force Microscopy (AFM) and optical tweezers (OT) have capability of measuring molecular level interactions with high spatial resolution. Molecular origin of biomechanical properties of cartilage probed by direct force measurement using AFM will be briefly reviewed. In another example of a biological system, mechanical unfolding and refolding behaviors of an adhesion molecule, integrin, were investigated at the single molecule level using OT. The integrin is a heterodimer transmembrane protein that plays a critical role in cellular adhesion and migration during the inflammation and immune response. When the I domain of integrin is mechanically stretched, the two step unfolding behavior with different extension distances occurred in a specific order indicating that there are two sub-domains in the I domain with different mechanical properties. In force-clamping experiments, a quasi-stable intermediate state was observed, which suggests that such intermediate is on-pathway to the folded state. The identity of the intermediate state and the force-bearing region of the I domain are discussed based upon structural analysis of integrin I domain. Lastly, the applications of single molecule techniques in the area of peptide self-assembly, gene delivery, and neurodegenerative disease will be presented with preliminary data.
