beta-carbonic anhydrase from Pisum sativum: crystallization and preliminary X-ray analysis.

Recombinant beta-carbonic anhydrase from the garden pea, Pisum sativum, was purified to homogeneity and crystallized. Crystals belong to the orthorhombic space group C222, with unit-cell parameters a = 136.3, b = 142.5, c = 201.4 A, alpha = beta = gamma = 90 degrees. Crystals typically diffracted anisotropically, with a maximal resolution of 2.0 A in the strongest direction. The calculated Matthews parameter predicts approximately eight molecules in the asymmetric unit, consistent with previous reports of the molecule being an octamer. However, examination of the self-rotation function revealed no fourfold symmetry axis and multiple weak twofold axes perpendicular to the crystallographic c axis, indicating that the oligomerization arrangement is not that of a 422 octamer.