Research Interests

I am a biophysicist with an avid interest in understanding how Nature's nanoscale machines work. I got my start studying the remarkable rotary engine that powers bacterial flagella, which is driven by a transmembrane current of protons. I then worked on myosin, the protein responsible for muscle contraction, which is driven by the hydrolysis of ATP. That experience led me to study an even smaller ATP-based mechanoenzyme, kinesin, which transports tiny organelles along microtubules inside cells. My laboratory pioneered the development of instrumentation based on optical traps (laser-based 'optical tweezers') that could resolve the individual steps taken by single kinesin molecules, which measure 8.2 nanometers. Steady improvements in technology eventually led to the detection of the even smaller steps made by single molecules of RNA polymerase as these move base by base along a DNA template, and which measure just 3.4 ? (angstroms). Using optical traps, we can now follow-with great precision-structure formation in individual biological macromolecules, such as folding and unfolding transitions in nascent RNA. Today, the field now known as "single molecule biophysics" is thriving, thanks to the advent of new methods of investigation and the successful partnership of physics and biology.

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Primary Section

Section 29: Biophysics and Computational Biology

Secondary Section

Section 13: Physics