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.