Crystallization and preliminary X‐ray crystallographic analysis of phosphoribulokinase from Rhodobacter sphaeroides

A recombinant form of Rhodobacter sphaeroides phosphoribulokinase (PRK), expressed in Escherichia coli and isolated by affinity chromatography, was crystallized by the sitting drop vapor diffusion technique using NH 4 H 2 PO 4 (pH 5.6) as the precipitating agent. PRK crystallizes in the cubic space group P432, with unit cell parameters a = b = c = 129.55 Å. Based on the assumption of one 32‐kDa monomer per asymmetric unit, the V m value is 2.83 Å 3 /Da. The octameric molecular symmetry is consistent with two planar tetramers stacked in a nearly eclipsed arrangement. A native data set has been collected to 2.6 Å resolution.