DNA as a Rubber Band: Single-Molecule DNA Stretching Using Optical Tweezers

The development of techniques to manipulate single molecules has led to large efforts to precisely study the mechanical and elastic properties of biomolecules such as proteins, protein fibers, DNA and RNA. Optical tweezers are a widely used technique in this area. They are sensitive in a biologically highly interesting force range: forces of typically a few hundred picoNewtons down to fractions of a picoNewton can be applied and measured using optical tweezers. This has allowed for, among other things, the precise measurement of forces and displacements exerted by individual ?motor proteins?, enzymes responsible for the conversion of chemical into mechanical energy in biology. In this report, we focus on the use of optical tweezers for force spectroscopy on single DNA molecules, and on the range of applications that this technique offers to learn not only about DNA itself, but also about the mechanics and thermodynamics of protein - DNA interaction.