Example 2
Recombinant human fascin 1 was expressed as a GST fusion protein in BL21 Escherichia coli. One liter of 2YT medium with ampicillin was inoculated overnight with 3 mL of BL21/DE3 culture transformed with pGEX4T-fascin 1 plasmid and grown at 37° C. until attenuance at 600 nm (D600) reached about 0.8. The culture was then transferred to 18° C. and induced by the addition of 0.1 mM isopropyl β-d-thiogalactoside (IPTG) for 12 h. Bacteria were harvested by centrifugation at 5,000 r.p.m. for 10 min. The pellets were suspended in 30 mL of PBS supplemented with 0.2 mM PMSF, 1 mM DTT, 1% (v/v) Triton X-100 and 1 mM EDTA. After sonication, the suspension was centrifuged at 15,000 r.p.m. for 30 min to remove the cell debris. The supernatant was then incubated for 2 h with 4 mL of glutathione beads (Sigma) at 4° C. After extensive washing with PBS, the beads were resuspended in 10 mL of thrombin cleavage buffer (20 mM Tris-HCl pH 8.0, 150 mM NaCl, 2 mM CaCl2, 1 mM DTT). Fascin was released from the beads by incubation overnight with 40-100 U of thrombin at 4° C. After centrifugation, 0.2 mM PMSF was added to the supernatant to inactivate the remnant thrombin activity. The fascin protein was further concentrated with a Centricon® (Boca Raton, FL) filter to about 50 mg/mL.
