Crystallization and preliminary X-ray structure solution of Rhizomucor miehei aspartic proteinase

Rhizomucor miehei aspartic proteinase (M_r = 38701, 361 residues) has been crystallized in a form suitable for analysis by X-ray diffraction. The flattened rod-shaped crystals were grown from polyethylene glycol 8000 using vapour-diffusion methods. The crystal form is in space group P2₁212₁ [a = 41.67 (2), b = 51.21 (3) and c = 173.3 (2) Å], with Z = 4 and one molecule in the asymmetric unit. Data were collected over the range 0 < h < 14, 0 < k < 16 and 0 < l < 62, resulting in 7032 unique reflections to give 72.1% completeness with a merging R of 0.067 to a resolution limit of 2.8 Å. A molecular-replacement solution of the structure has been obtained using the aspartic proteinase from Rhizomucor pusillus as a model. Rigid-body refinement of the model and subsequent refinement using molecular dynamics were performed with X-PLOR, leading to a current R-factor of 20.1% for 2.8 Å data.