Force spectroscopy experiments were conducted on a custom-built magnetic
tweezers apparatus, as previously described17 (link). The experimental fluid chambers are placed on the top
of an inverted microscope (Olympus IX-71/Zeiss Axiovert S100) and illuminated
with a collimated cold white LED (ThorLabs). The reference beads and the
protein-bound paramagnetic beads are visualized employing a 100X oil-immersion
objective (Zeiss/Olympus), which is mounted on a nanofocusing piezo actuator
(P-725; Physik Instrumente). Image acquisition was done using a CMOS Ximea
MQ013MG-ON camera, and image processing was done with custom-written C++/Qt
software. Data acquisition and piezo position control were done using a
multifunction DAQ card (NI USB-6289, National Instruments). Proteins were
exposed to calibrated forces using a pair of magnets mounted on the top of a
voice-coil (Equipment Solutions) placed above the experimental fluid chamber.
Magnets position was maintained under electronic feedback with a PID
controller.
tweezers apparatus, as previously described17 (link). The experimental fluid chambers are placed on the top
of an inverted microscope (Olympus IX-71/Zeiss Axiovert S100) and illuminated
with a collimated cold white LED (ThorLabs). The reference beads and the
protein-bound paramagnetic beads are visualized employing a 100X oil-immersion
objective (Zeiss/Olympus), which is mounted on a nanofocusing piezo actuator
(P-725; Physik Instrumente). Image acquisition was done using a CMOS Ximea
MQ013MG-ON camera, and image processing was done with custom-written C++/Qt
software. Data acquisition and piezo position control were done using a
multifunction DAQ card (NI USB-6289, National Instruments). Proteins were
exposed to calibrated forces using a pair of magnets mounted on the top of a
voice-coil (Equipment Solutions) placed above the experimental fluid chamber.
Magnets position was maintained under electronic feedback with a PID
controller.
