Methods & Equipment

Cell Growth and Cultivation

Work in the group is centered on prokaryotic systems from a wide range of different source organisms. We are cultivating microorganisms in batch culture using flasks and fermentors under control of atmosphere and gas flow. 

Anoxic Protein Biochemistry

Due to the oxygen sensitivity of most proteins under investigation we are using modified Schlenk techniques and inert gas chambers to work under strict exclusion of dioxygen. Several systems, in particular nitrogenase and nitrous oxide reductase, require that all steps of our studies be carried out anoxically, including crystallization and crystal mounting.

For protein purification we use a variety of ÄKTA prime, ÄKTA Purifier/Explorer and ÄKTA Pure systems. Advanced protein characterization is carried out with a Malvern/Viscotek GPC system with triple detector array.

Protein Crystallization

In order to obtain large, well-diffracting single crystals we use nanoliter liquid handling systems (Douglas Instruments Oryx Nano, Rigaku Phoenix RE) and screen makers (Rigaku Alchemist II). Automated and scheduled inspection of crystal images is made with a Rigaku Minstrel HT UV system at 4°C or 20°C, respectively. 

X-ray Diffractometry

As the central method of the groups is the determination of three-dimensional, atomic structures using X-ray diffractometry, we are equipped with state-of-the art facilities, a Rigaku Micromax 007HF microfocus X-ray generator and CCD and image plate detectors. The group has excellent access to the Swiss Light Source (SLS) and the European Synchrotron Radiation Facility (ESRF). 

Spectroscopy

Proteins containing transition metals are ideal targets for spectroscopic studies. Besides UV/vis and NIR spectroscopy we are using electron paramagnetic resonance (EPR). The group has a Bruker Elexsys 500 continuous-wave spectrometer to operate at X-band or Q-band, equipped with a helium cryostat. For studying the frequently anisotropic absorption properties of crystals (dichroism) and the effects of possible photoreduction during X-ray irradiation we have a 4DX microoptics system with an ANDOR spectrograph.

Calorimetry

Determination of affinity constants and thermodynamic parameters is often essential for understanding the functional properties of an enzyme. We are using isothermal titration calorimetry (ITC) for direct thermodynamic measurements.