Crystallization and preliminary X-ray diffraction analysis of the electron-transfer complex between the terminal oxygenase component and ferredoxin in the Rieske non-haem iron oxygenase system carbazole 1,9a-dioxygenase.

Carbazole 1,9a-dioxygenase, which consists of an oxygenase component (CARDO-O) and the electron-transport components ferredoxin (CARDO-F) and ferredoxin reductase (CARDO-R), catalyzes dihydroxylation at the C1 and C9a positions of carbazole. The electron-transport complex between CARDO-O and CARDO-F crystallizes at 293 K using hanging-drop vapour diffusion with the precipitant PEG MME 2000 (type I crystals) or PEG 3350 (type II). Blossom-shaped crystals form from a pile of triangular plate-shaped crystals. The type I crystal diffracts to a maximum resolution of 1.90 A and belongs to space group P2(1), with unit-cell parameters a = 97.1, b = 89.8, c = 104.9 A, alpha = gamma = 90, beta = 103.8 degrees. Diffraction data for the type I crystal gave an overall Rmerge of 8.0% and a completeness of 100%. Its VM value is 2.63 A3 Da(-1), indicating a solvent content of 53.2%.