Properties of the detergent solubilised cytochrome coxidase (cytochrome cbb3) purified from Pseudomonas stutzeri

Cytochrome cbb3is a cytochrome c‐oxidising isoenzyme that belongs to the superfamily of respiratory haem/copper oxidases. We have developed a purification method yielding large amounts of pure cbb3complex from the soil bacterium Pseudomonas stutzeri. This cytochrome cbb3complex consists of three subunits (ccoNOP) in a 1:1:1 stoichiometry and contains two b‐type and three c‐type haems. The protein complex behaves as a monomer with an overall molecular weight of 114.0±8.9 kDa and a s020,wvalue of 8.9±0.3 S as determined by analytical ultracentrifugation. Crystals diffracting to 5.0 Å resolution have been grown by the vapour diffusion sitting drop method to an average size of 0.1×0.1×0.3 mm. This is the first crystallisation report of a (cbb3)‐type oxidase.