BL21(DE3) Competent Cells

BL21-gold competent cells feature the high transformation efficiency phenotype (Hte) and have the gene encoding endonuclease I (endA) inactivated. Together, these two features allow direct cloning for most protein expression constructs. By cloning directly in the strain, you can save two days of work normally spent on subcloning procedures. The DE3-derivatives of BL21 contain the T7 RNA polymerase gene controlled by the lacUV5 promoter. This all-purpose derivative yields high-level expression and provides easy induction. Use this derivative with nontoxic proteins.