400 Dowman Dr.
Math and Science Center
Room: N246
Phone: 404-727-4930
Email: lfinzi@emory.edu
Magnetic tweezers (MTs)
Magnetic tweezers (MTs) permit modulation in the level of supercoiling within a DNA tether. MTs, most commonly consist of a pair of magnets placed on a mount above the microscope stage that can be both translated along or rotated around the optical axis of the microscope. The magnetic field generated by the magnets both attracts and rotationally traps a DNA-tethered paramagnetic bead. This results in stretching the DNA tether, and by rotation of the magnets, the DNA becomes positively or negatively supercoiled (Figure below).
The figure represents a schematic representation of a magnetic tweezer set-up. The DNA is represented as a black curved line tethering an orange paramagnetic bead to the glass surface of a microscope flow-chamber. Above the sample there are two magnets that can be both translated vertically along the microscope optical axis and / or rotated. Since the bead aligns rigidly in the magnetic field, one turn of the magnets causes one turn of the bead, which corresponds to one twist in the tethering DNA molecule.
Follow the link to Research/Methods/MTs to see how we improved this technique.