SUNY at Albany
June 19-23, 2001
Exploring the free energy landscape of a biomolecular bond
Force probe techniques like atomic force microscopy can directly measure the force required rupturing single biological ligand receptor bonds. Such forces are related to the energy landscape of these weak, non-covalent biological interactions. We discuss models for the force-induced dissociation of a ligand-receptor bond, occurring in the context of cell adhesion or single molecule unbinding force measurements. We consider a bond with a structured energy landscape, which is modelled by a network of force dependent transition rates between intermediate states. We calculate the bond lifetime as a function of an applied force and unbinding forces under an increasing applied load and determine the relationship between both quantities. The dissociation via an intermediate state can lead to distinct functional relations of the bond lifetime on force. We also report unbinding force measurements between complementary strands of DNA as a function of temperature. Our measurements suggest a separation of enthalpic and entropic contributions to the energy landscape of the bond.
Torsten Strunz, Irina Schumakovitch, Wilfried Grange, Hans-Joachim G?ntherodt, Martin Hegner
Department of Physics and Astronomy, Biophysics group, University of Basel, Klingelbergstrasse 82, CH - 4056 Basel, Switzerland,