| X-RAY DIFFRACTION |
? |
293.0 |
Crystals used for seeding were obtained by vapor diffusion at 20 degrees C with 25 nl of 11 mg/ml (delta)ABD-p110(delta) and 0.9 mM of a p110(delta) inhibitor in protein storage buffer (20 mMTris, pH 7.2, 50 mM (NH4)2SO4, 1% v/v ethylene glycol, 1% (w/v) betaine, 0.3 microM CHAPS, and 5 mM TCEP) added to 25 nl of reservoir solution (25% (w/v) PEG 3350, 0.1 M bis-tris (pH 6.5). Crystals were pulverized, pooled together in the reservoir solution, vortexed with a Seed-Bead (Hampton Research) for 45s, flash-frozen in liquid nitrogen, and stored at -80 degrees C. For seeding crystallization trials, the frozen seed was thawed and diluted 500-fold in 25% (v/v) PEG 300, 0.1 M Tris (pH 8.5).
Preparation of diffraction quality (delta)ABD-p110(delta):GS-9901 crystals started with a mixture of 0.48 microL of 2.5% (w/v) n-dodecyl-(beta)-D-maltoside, 0.30 microL of 20 mM ligand, and 12 microL of 12 mg/ml (delta)ABD-p110(delta) in storage buffer (described above). The mixture was allowed to sit for 1 h at room temperature instead of 4 degrees C to prevent the formation of white precipitate. Seeded vapor diffusion droplets were assembled by adding 90 nl of the 500-fold diluted seed (described above) to 100 nl of the n-dodecyl-(beta)-D-maltoside-ligand-(delta)ABD-p110(delta) mixture. The droplets were equilibrated against reservoir wells containing 50 microL of 1% to 30% (v/v) PEG 300, 0.1 M Tris (pH 8.5) at 20 degrees C. Crystals appeared in 2-5 days across the 1% to 30% PEG range. Crystals were cryoprotected in 20% (w/v) glycerol, 25% (w/v) PEG 300, 0.1 M Tris (pH 8.5), 50 mM ammonium sulfate, 0.2% (w/v) n-dodecyl-(beta)-D-maltoside, 0.2 mM ligand and were flash-frozen in liquid nitrogen for data collection. |
