Access Type

Open Access Dissertation

Date of Award

January 2011

Degree Type


Degree Name



Physics and Astronomy

First Advisor

Peter M. Hoffmann


Single-molecule approaches to measuring the kinetics of protein dissociation have the advantage that measurements can be performed in native environments, such as living cells, where concentrations of target molecules may be quite low. In addition, single molecule approaches allow for the measurement of variances in protein kinetics, thus providing a more complete picture of protein kinetics than ensemble techniques which typically only provide averages.

In our laboratories, we use the force spectroscopy (FS) technique to study protein binding and dissociation. FS measures the strength of the protein molecules bond with high resolution down to pico-Newton either on the surface of solid substrate or the membrane of living cells. However, the interpretation of force measurements of single molecule dissociation continues to be controversial, although significant progress has been made recently. The main concerns involve the role of multiple attachments, nonlinearity of the applied force profile, and possible changes in binding conformation. Because of these uncertainties, force measurements have not been used widely for biological and medically relevant systems. Accordingly, our research aims to achieve three main goals: First to perform single molecular experiments using model system like avidin and biotin; Secondly to improve the theory that is used to analyze the force data, so the mechanism of binding and dissociation of the molecular bonds, as well the extracted dissociation rate can be more reliably determined; Thirdly to utilize the extended theory to investigate relevant enzyme-inhibitor systems under physiological conditions.

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