Overnight cultures of E. coli BL21(DE3) harbouring pET-LipBL and pETLipBL-variant
expression vectors were used to inoculate 50 ml LB
broth supplemented with kanamycin (30 mg ml21
). Cultures were
incubated under aerobic conditions at 37 uC to OD600 0.6, followed
by induction with IPTG (1 mM final concentration) and further
incubation under the same conditions for 3 h at 30 uC. Harvested
cells (7500 g, 10 min, 4 uC) were resuspended in 50 mM Tris/HCl,
pH 8.0. Cells were disrupted by two cycles of sonication for 2 min
followed by two centrifugation steps, first at 5000 g for 1 min (4 uC)
to remove intact cells and cell debris and then at 16 000 g for 10 min
(4 uC) to collect inclusion bodies. The supernatants were used as a
source of intracellular soluble proteins.