   7.3.2.5 | ModA in the apoprotein conformation and in the molybdate-bound conformation, by sitting-drop and hanging-drop vapor-diffusion methods, mixing of 0.001 ml of protein solution containing 16-23 mg/ml protein with 0.001 ml reservoir solution, containing 1.4 M ammonium citrate pH 6.4 or 1.4 M ammonium citrate pH 6.0, 4 mM sodium sulfate for the apo-protein and 2.1 M ammonium sulfate and either 1% v/v or 3% v/v 2-propanol, and 4% v/v 2.4 M ammonium sulfate for the molybdate-bound protein, equilibration against 100 ml reservoir solution at room temperature for apo-odA and at 293 K for molybdate-bound ModA, 1 week, method optimization, X-ray diffraction structure determination and analysis of apo- and molybdate-bound-ModA at 1.95 A and 1.69 A resolution and at 2.25 A and 2.45 A resolutionm, respectively, molecular replacemen fails, usage of heavy metal labeling instead |
