| X-RAY DIFFRACTION |
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293 |
Using a commercial crystal screen (HAMPTON RESEARCH, HR2-130) yielded a hit for monophosphorylated HRas under sitting drop conditions (drop size 600 nL) with a 1:1 ratio of protein solution (phospho-HRas 0.4 mM, RasGAP 0.4 mM, Na-HEPES 20 mM pH = 8.0, MgCl2 5 mM, NaF 20 mM) and precipitant (Na-citrate 100 mM pH = 5.6, Li2SO4 1.0 M, CaCl2 200 mM). After three rounds of microseeding well-formed single crystals were obtained using 2.0 uL sitting drops and a 1:1 ratio of protein buffer (HRas 400 uM, RasGAP 400 uM, MgCl2 5 mM, Na-HEPES 20 mM pH = 8.0, NaF 20 mM) and precipitant (Na-Citrate 100 mM pH = 5.6, Li2SO4 800 mM, CaCl2 200 mM). These were harvested using cryoprotectant (80% precipitant, 20% glycerol (v/v)) and sent for data collection. |
