Crystallization and Preliminary X-ray Diffraction Studies of a NADH Oxidase from Thermus thermophilus HB8

Abstract 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 P 4 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.