Crystallization and preliminary X-ray crystallographic studies of 7α-hydroxysteroid dehydrogenase from Escherichia coli

Crystals of 7α-hydroxysteroid dehydrogenase from E. coli, which is a tetramer in its active form, have been obtained by a hanging-drop vapor-diffusion method in the presence of the coenzyme NAD⁺. Crystals as large as 0.25 × 0.25 × 0.75 mm could be grown within a month at pH 8.5 with polyethylene glycol as precipitating agent. Preliminary X-ray crystallographic analysis revealed that they belong to one of the enantiomorphic space groups P4₁2₁2 or P4₃2₁2 with dimensions a = b = 81.66 and c = 214.6 Å, having two subunits in an asymmetric unit. The crystals diffract to at least 2.3 Å resolution.