Laser based optical tweezers

The step size of a myosin motor can be calculate by laser based optical tweezers. In this approach the myosin is bound at low density to an immobilised bead. An actin filament, which is held by two laser based light sources, is lowered towards the bead. When myosin touches the actin filament and ATP is added the ATPase cycle is stimulated and myosin moves the actin filament. The distance and force by which it does this can be calculated via the computer running the microscope.