Proceedings of the National Academy of Sciences of the United States of America

About the PNAS Member Editor
Name Block, Steven M.
Location Stanford University
Primary Field Biophysics and Computational Biology
Secondary Field Physics
 Election Citation
Block, a pioneer in the field of single-molecule biophysics and a leader in the design of optical traps, was the first to show that molecular motors take finite steps. His research on how nanoscale machines work led to the development of laser-based "optical tweezers," which have enabled scientists to explore the behavior of individual macromolecules.
 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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