| X-RAY DIFFRACTION |
7.0 |
293 |
The protein was concentrated to 20 mg/ml and dialyzed against 5 mM HEPES, 2 mM MgCl2, 50 mM NaCl, 0.25 mM TCEP, 1 mM NaN3, pH 7.0, drop frozen as small pellets in liquid nitrogen and stored at -80 C. The frozen concentrated protein was thawed and diluted to 10 mg/mL with 5 mM HEPES, 2 mM MgCl2, 1 mM NaN3, pH 7.5. A stock solution of the peptide substrate L-Ala-L-Glu (Sigma) was neutralized to pH 7.5 with NaOH and brought to a final concentration of 1.6 M. This solution was added to the protein as 1/50th part by volume and the resultant mixture utilized for crystallization experiments. The initial crystals were grown by hanging drop by mixing 5 ?l of protein solution and 5 ?l of a solution containing 9-11% dimethyl-PEG 5000, 50 mM MOPS, 1% MPD, 1 mM NaN3, pH 7.0 and suspending the droplets over 600 ?l precipitant at 20 C, VAPOR DIFFUSION, HANGING DROP, temperature 293K |
