"The Manipulation of Single Biomolecules
published in Physics Today, October 2001

By monitoring the response of individual protein and DNA molecules to pulling and twisting, biophysicists can learn much about their structure and their interactions.

Twenty-five years ago, neurophysiology was revolutionized by the invention of a clever way to record the electrical activity of a single ionic channel across a membrane. This so-called patch-clamp technique earned its inventors, Erwin Neher and Bert Sakmann, a Nobel Prize. The statistical analysis of the current flowing like a noisy telegraphic signal through such a channel yielded precious and unique information on the dynamic states of these channels. That information had previously been blurred or lost when, as was the prior custom, one simply measured the average current flowing through a large ensemble of channels.

Biophysics is undergoing a similar transformation, thanks to the development of new tools for manipulating, visualizing, and studying single molecules and their interactions. The statistical analysis of the measured signals (often a sequence of noisy steps) lets the biophysicist learn about the step size of molecular motors, their energy consumption, and the rate-limiting transitions in their enzymatic cycles. One can thus build and verify better models of how these enzymes function."

Physics Today October 2001