Expression, purification, crystallization, and preliminary X-ray diffraction analysis of the homodimeric bacterial hemoglobin from Vitreoscilla stercoraria

The recombinant homodimeric hemoglobin from the strictly aerobe gram- negative bacterium Vitreoscilla stercoraria has been expressed in Escherichia coli, purified to homogeneity, and crystallized by vapor diffusion techniques, using ammonium sulfate as precipitant. The crystals belong to the monoclinic space group P2₁ and diffract to HIGH resolution. The unit cell parameters are a = 62.9, b = 42.5, c = 63.2 Å, β = 106.6°; the asymmetric unit contains the homodimeric hemoglobin, with a volume solvent content of 42%.