| X-RAY DIFFRACTION |
8.0 |
277 |
Crystallization of native human prostacyclin synthase (hPGIS). The native recombinant PGIS (25 mg/ml in the gel filtration buffer containing 20 mM Tris, pH 8.0 and 150 mM NaCl) was found to crystallize spontaneously into needle clusters in the Eppendorf tube when stored at 4 C for about a week. A combination of microseeding technique and the hanging-drop vapor-diffusion method was then used to improve crystal quality. Specifically, seed stock was prepared by crushing these initial PGIS needle clusters with the Seed Bead Kit (Hampton Research). Following four 10-fold serial dilutions of the seed stock using the gel filtration buffer, 1 microliter of diluted seeds was added into a 10 microliter drop of freshly concentrated PGIS sample, and equilibrated at 4 C against 450 microliter of the gel filtration buffer.
Crystallization of hPGIS-minoxidil complex: The inhibitor-enzyme complex was prepared by adding minoxidil (final concentration 0.1 mM) to a 20 mg/ml hPGIS stock solution. Crystals of the complex were then obtained by co-crystallization, with the technique described above using ligand-free hPGIS microcrystals as seeds., VAPOR DIFFUSION, HANGING DROP, temperature 277K |
