| X-RAY DIFFRACTION |
5.5 |
291 |
Following cell lysis, the protein was extracted by Ni-NTA Superflow FF, followed by TEV protease cleavage in buffer (200 mM NaCl, 1 mM BME, 20 mM NaP (NaH2PO4+Na2HPO4, pH 7.1). Further purification included Ni-NTA, MonoS and Gelfiltration (in 200 mM NaCl and 20 mM NaP buffer pH 6.5). Purified PrfA was co-crystallized with complex (5 mol excess) using the hanging-drop vapor-diffusion technique. Crystals grew in 5 days after 2 microL of the protein solution (3.2-3.5 mg per ml PrfA, 200 mM NaCl, 20 mM NaP buffer, pH 6.5) was mixed with an equal volume of precipitant solution containing 20-24% PEG-4000, 17% isopropanol, 100 mM Na citrate pH 5.5 and allowed to equilibrate over a 1 ml solution of the precipitant in a Linbro plate (Hampton Research). |
