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 d1 haem as prosthetic groups. A new crystal from 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 group P4(1(3))2(1)2 and cell dimensions a = b = 128.2 A, c = 172.6 A. They diffract at least up to 2.8 A. Assuming a dimer in the asymmetric unit, the VM value is 2.95 A3/Da (58% of solvent).