Proteins are expressed in E. coli in 1.5L of TB media supplied with Ampicillin and induced with 0.6mM IPTG for overnight at 25C. Cells are harvested by 10 min centrifugation at 8K rpm. Pellets resuspended in Lysis Buffer (43mM Na2HPO4, 3.25mM Citric acid, 250mM NaCL, 100mM Ammonium Sulfate, 5% Glycerol, 5mM Imidazole, 1.5mM Magnesium acetate, 1mM CaCL2, 0.08% DDM, 5mM b-mercaptoethanol) pH 7.8. Suspension then frozen at -30C. Cell extract for protein purification is obtained by sonication of previously frozen cell suspention in lysis buffer with follow up ultracentrifugation at 18K rpm, 4C for 40 min.