Crystallization and characterization of the prolidase from Pyrococcus furiosus

The prolidase (proline-specific amino dipeptidase) from the hyperthermophilic archaeon Pyrococcus furiosus has been crystallized. The enzyme has been shown to be a homodimer and to require two Co atoms per subunit for optimum activity. Two crystal forms have been obtained under similar growth conditions. Both are monoclinic, space group P2(1). Form I has unit-cell parameters a = 130.4, b = 97.4, c = 129.9 A, beta = 118.3 degrees. Form II has a smaller unit cell, with a = 56.5, b = 97.3, c = 70.0 A, beta = 97.1 degrees. If the crystal density is assumed to lie near the center of the normal range then the form I crystals will have four dimers per asymmetric unit, whereas the form II crystals will have only one dimer in each asymmetric unit. Diffraction data have been recorded from native form I and form II crystals to resolutions of 3.2 and 1.95 A, respectively.