Crystallization and preliminary X-ray diffraction analysis of fatty-acid hydroxylase cytochrome P450BSβ from Bacillus subtilis

Cytochrome P450 isolated from Bacillus subtilis (P450BSβ; MW 48 kDa) catalyzes the hydroxylation of long-chain fatty acids at the α and β positions using H₂O₂ as an oxidant. Crystals of the substrate-free form of P450BSβ belonging to the trigonal space group P3₂21 or P3₁21 were obtained by the sitting-drop vapour-diffusion method using a precipitate solution consisting of 10%(w/v) PEG 4000 and 50 mM MES pH 6.8. Another crystal form, belonging to the rhombohedral space group R3 or R32, was obtained from precipitate solution consisting of 10% PEG 4000, 0.15 mM magnesium acetate and 50 mM MES pH 6.5 in the presence of 2 mM myristic acid (substrate). Using synchrotron radiation, both P450BSβ crystals diffracted to 2.5 Å resolution. Bijvoet and dispersive anomalous difference Patterson maps show a clear peak corresponding to the haem iron.