Preliminary X-ray diffraction studies on a ferredoxin from the thermophilic archaebacterium, Thermoplasma acidophilum

A ferredoxin from the thermophilic archaebacterium, Thermoplasma acidophilum, is supposed to contain two (4Fe-4S) active centers; one center could be linked by four cysteine residues to the protein and the other bonded with three cysteines and an unknown group. This ferredoxin has been crystallized by salting-out against 2.3 M-ammonium sulfate solution. The space group is P21212 with cell dimensions of a = 59.20 A, b = 52.77 A and c = 41.28 A. Four molecules pack in the unit cell with Vm = 2.03 A3/dalton.