Crystallization and preliminary crystal data of iron-containing superoxide dismutase from Pseudomonas ovalis

Large single crystals of iron-containing superoxide dismutase from Pseudomonas ovalis were prepared from 50% saturated ammonium sulfate solution, at pH 4.5, on gentle evaporation of the solvent at 4 degrees. The crystals were monoclinic, space group P2, with unit cell dimensions a = 81.9 A, b = 49.0 A, c = 61.0 A, and beta = 106 degrees. Considerations of cell volume and protein molecular weight indicated 1 molecule of superoxide dismutase in the assymmetric unit, the smallest number reported so far for superoxide dismutases.