Single-Molecule Pulling Experiments: Theory, Analysis and Interpretation

Professor Olga K. Dudko
Department of Physics
and NSF Center for Theoretical Biological Physics
UC San Diego


Mechanical forces are generated during nearly every facet of the cell cycle. Recent advances in experimental techniques enable experimentalists to exert forces on individual molecules and observe their response in real time. Thus, the single-molecule approach has changed the way many physical, chemical and biological problems are addressed. We present a theory for extracting kinetic information from single-molecule pulling experiments at constant force or constant loading rate. Our procedure provides estimates of not only i) the intrinsic rate coefficient and ii) the location of the transition state, as in the widely used phenomenological approach based on Bell's formula, but also iii) the free energy of activation. We illustrate the use of our approach by applying it to sets of data obtained from nanopore unzipping of individual DNA hairpins and from unfolding of single protein molecules with the atomic force microscope.