| X-RAY DIFFRACTION |
8.0 |
277 |
The native recombinant PGIS (25 mg/ml in the 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 micro-l of diluted seeds was added into a 10
micro-l drop of freshly concentrated PGIS sample, and equilibrated at 4 C against 450 micro-l of the
gel filtration buffer. High quality single crystals of PGIS were most often obtained using 100- or
1000-fold diluted seed stock, and reached suitable size (~ 0.05,0.05 ~ 0.1 mm3) within one week.,
VAPOR DIFFUSION, HANGING DROP, temperature 277K |
