BL21(DE3) competent cell are expression hosts for protein production using the T7 promoter. The (DE3) designation indicates that the host is a lysogen of λ(DE3), and therefore carries a chromosomal copy of the T7 RNA polymerase gene under control of the lacUV5 promoter. Such strains are required for protein expression from target genes cloned in T7 expression vectors. BL21(DE3) is the most widely used host for protein expression because it is deficient in the Lon and OmpT proteases.
- Strain : BL21(DE3)
- E. coli B strain with DE3, a λ prophage carrying the T7 RNA polymerase gene and lacIq
- Genotype : F– dcm ompT hsdS (rB- mB-) gal λ(DE3)
- Prepared using an optimized chemical method
- T7 promoter protein expression
- Whole genome sequence
- Transformation efficiency : ≥1.6 × 106 cfu/μg of pUC19
- Transformation should be started immediately after the cells have thawed on ice.
- Do not use a pipette when thawing competent cells or mixing DNA samples with cells.- Do not freeze competent cells once thawed