Protein Expression Using BL21 ( DE3 ) ( C2527 )
Transform expression plasmid into BL21 ( DE3 ) .
Plate on antibiotic selection plates .
Incubate overnight at 37°C .
Resuspend a single colony in 10 ml liquid culture with antibiotic .
Incubate at 37°C until OD600 reaches 0.4–0.8 .
Induce with 4 or 40 µl of a 100 mM stock of IPTG ( final concentration of 40 or 400 µM ) Induce for 3 to 5 hours at 37°C .
Check for expression either by Coomassie stained protein gel , Western Blot or activity assay .
Check expression in both the total cell extract ( soluble + insoluble ) and the soluble fraction only .
