Expression of the MBP fusion protein was carried out as previously described [14, 49] . Briefly, Escherichia coli BL21(DE3) cells transformed with the MBP-BLV-hairpin vector were grown at 37uC with vigorous shaking in LB supplemented with 10 mM glucose and 100 mgml 21 ampicillin until an optical density at 600 nm of ,0.6 was reached. Protein expression was induced with Isopropylthio-b-D-galactoside (IPTG) at a final concentration of 0.5 mM for 4 h at 37uC. Cells were harvested by centrifugation and the pellet was resuspended in column buffer (20 mM Tris-HCl [pH 7.5], 200 mM NaCl, 1 mM EDTA) supplemented with protease inhibitors (1 mM phenylmethylsulfonyl fluoride and 1 mgml 21 aprotinin) and frozen O/N at 220uC. The cell suspension was thawed and the cells lysed by sonication. Cell debris was pelleted by centrifugation at 9,0006g for 30 min. The crude lysate was diluted 1:5 in column buffer and loaded onto an amylose column pre-equilibrated with column buffer. The column was then washed with 15 column volumes of column buffer, and the bound protein was eluted with column buffer supplemented with 10 mM maltose.