Crystallization and preliminary X-ray diffraction studies of a NADH oxidase from Thermus thermophilus HB8

The thermophile NADH oxidase from Thermus thermophilus, cloned and expressed in Escherichia coli, has been purified to homogeneity and crystallized. Three different crystal forms were found to be suitable for X-ray diffraction analysis. Crystals of the tetragonal form, grown in the presence of 25% polyethylene glycol 4000 and 0.25 M-NaCl at pH 6.6, were chosen for further analysis. These crystals belong to the space group P4(1)(3)2(1)2 with refined lattice constants of a = 94.8 A and c = 49.0 A, indicating a cell content of one monomer per asymmetric unit of the crystal. The crystals diffract to a resolution of 2.2 A.