Crystallization of CMY-185 β-Lactamase

Prior to the crystallization, the purified CMY-185 recombinant enzyme was diluted to the final concentration of 15 mg/mL in 20 mM Tris-HCl pH 7.0. Crystals of CMY-185 were obtained using hanging-drop vapor diffusion method with the crystallization condition in which the CMY-185 solution was mixed with an equal volume of a reservoir solution containing 24% PEG 20,000, 0.1 M Tris-HCl pH 8.5, and 0.2 M lithium sulfate at 20°C. Crystals of the CMY-185-ceftazidime complex were obtained by soaking the CMY-185 crystals in a solution containing 100 mM ceftazidime, 26% PEG 20,000, 0.1 M Tris-HCl pH 7.0, and 0.2 M lithium sulfate at 4°C for 4 h.