----------------------------------------------------------------------- BIOINFORMATICS COLLOQUIUM School of Computational Sciences George Mason University ----------------------------------------------------------------------- Dynamics of unbinding of cell adhesion molecules: Transition from catch to slip bonds Dr. Valeri Barsegov Faculty Research Associate Institute for Physical Science and Technology University of Maryland at College Park Tuesday, November 29, 2005 4:30 pm Verizon Auditorium, Prince William Campus ABSTRACT The unbinding dynamics of complexes involving cell adhesion molecules depends on the specific ligands. Atomic force microscopy measurements have shown that for the specific P-selectin-P-selectin glycoprotein ligand (sPSGL-1) the average bond lifetime initially increases (catch bonds) at low (<10pN) constant force, f, and decreases when f>10pN (slip bonds). In contrast, for the complex with G1 anti-P-selectin monoclonal antibody monotonically decreases with f. To map the energy landscape of such complexes we use a model that considers the possibility of redistribution of population from one force-free state to a force-stabilized bound state. The excellent agreement between theory and experiments allows us to extract energy landscape parameters by fitting the calculated curves to the lifetime measurements. The theory for cell adhesion complexes can be used to predict the outcomes of unbinding of other protein-protein complexes. BIOSKETCH Undergraduate: Moscow State University, Diploma in Chemistry (1994); Experiment: Binding kinetics of delta-opioid ligands; cycle of G-protein; signal transduction Graduate: University of Nebraska at Lincoln, MS in Physical Chemistry (1996); Experiment: Nuclear quadrupolar studies of hydrogen bonds and rotational motion is organic crystals (Dept. of Chemistry) Graduate: University of Texas at Austin, PhD in Chemical Physics (2000); Theory: Quantum Brownian motion and quantum decoherence (with Prof. Ilya Prigogine, Dept. of Physics); Theory: Quantum-classical correspondence in non-adiabatic transitions (with Prof. Peter Rossky, Dept. of Chemistry and Biochemistry) Postdoctoral: University of Rochester (2001-2003); Theory: Single molecule optical spectroscopy; Kinetics/Dynamics of single biomolecules (Prof. Shaul Mukamel, Dept. of Chemistry) Postdoctoral: Institute for Physical Science & Technology, University of Maryland at College Park (since 2003); Theory: all-atom and Langevin simulations of cell-adhesion complexes; statistical analysis of protein unfolding/unbinding data (Prof. Devarajan Thirumalai) ----------------------------------------------------------------------- Refreshments are served at 4:00 pm. Find the schedule and directions at http://www.binf.gmu.edu/colloq.html