CRYSTALLIZATION AND PRELIMINARY-X-RAY ANALYSIS OF A NEW CRYSTAL FORM OF NITRITE REDUCTASE FROM PSEUDOMONAS-AERUGINOSA

Nitrite reductase from Pseudomonas aeruginosa (EC 1.9.3.2), a redox enzyme synthesized by the bacterium grown in the presence of nitrate, is a soluble dimer of two identical subunits of 60 kDa, each containing one c and one d(1) haem as prosthetic groups. A new crystal form of the Ps. aeruginosa nitrite reductase in the oxidized state, suitable for X-ray structure determination, has been obtained by vapour diffusion at 20 degrees C, in the presence of 10% polyethylene glycol 4000, 50 mM Tris-HCl (pH 8.7), 400 mM NaCl and at a protein concentration of 14 mg/ml. The crystals are dark green elongated tetragonal prisms of dimensions 1.5 mm x 0.2 mm x 0.2 mm for the largest ones. These crystals are tetragonal with space grou P4(1(3))2(1)2 and cell dimensions a = b = 1.28.2 Angstrom, c = 172.6 Angstrom. They diffract at least up to 2.8 Angstrom. Assuming a dimer in the asymmetric unit, the V-M value is 2.95 Angstrom(3)/Da (58% of solvent).