Speaker
Description
The neutron single crystal diffractometer BIODIFF, a joint project of the Forschungszentrum Jülich and the FRM II, is dedicated to the structure determination of enzymes. Typical scientific questions address the determination of protonation states of amino acid side chains in the active center, the orientation of individual water molecules essential for the catalytic mechanism and the characterization of the hydrogen bonding network between the enzyme active center and an inhibitor or substrate. BIODIFF is designed as a monochromatic diffractometer and is able to operate in the wavelength range of 2.0 Å to about 5.6 Å. This allows to adapt the wavelength to the size of the unit cell of the sample crystal. Without the cold source in place, BIODIFF can operate in the wavelength range of 2.0 Å – 2.7 Å with tolerable losses. The loss at 2.7 Å is approximately 50% compared to operation with the cold source. Recently, the former manual adjustable collimator positioning unit was replaced by a hexapod. This now allows for quick and automated adjustment of the collimation unit. Switching between different aperture setups is now easy via an exchangeable cassette insert. In addition, a new upgraded cryo-insert was installed. The new precise 1-circle goniometer in combination with a x,y,z-stage and mini-kappa-goniometer allows for efficient data collection in combination with the N2-cryo-stream. The new goniometer makes it possible to go beyond the so-called step-scan measurements and to move the omega-axis pseudo-continuously (micro-stepping mode) while the shutter is open. In addition, a potential detector upgrade for BIODIFF will be presented, which will expand the maximum unit cell limits.
