Dynamics of unbinding of cell adhesion molecules: Transition from catch to slip bonds

PHYS 468

Valeri Barsegov, valeri@glue.umd.edu and Devarajan Thirumalai. Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742
The unbinding dynamics of complexes involving cell adhesion molecules depends on the specific ligands. AFM measurements show that for the specific P-selectin glycoprotein ligand (sPSGL-1) the average bond lifetime initially increases (catch bonds) and then decreases (slip bonds) with force. To map the energy landscape of such complexes we use a model that considers the possibility of redistribution of population from force-free state to force-stabilized bound state. The excellent agreement between theory and experiments allows us to map energy landscape by fitting the calculated curves to the lifetime measurements for sPSGL-1. The unbinding transition state for P-selectin-sPSGL-1 complex is far (1.5nm) from the bound state, which is indicative of a compliant structure. The theory for cell adhesion complexes can be used to predict the outcomes of unbinding of other protein-protein complexes.
 

Poster Session
7:30 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Sci-Mix

Division of Physical Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006