E. cloni EXPRESS BL21(DE3) Electrocompetent Cells are the first to offer high efficiency cloning and high level protein expression in the same cell. Cloning efficiencies are increased 25-1,000 fold relative to competitors’ preparations of BL21 cells (Figure 1), which is essential for construction of complex expression libraries. The unprecedented transformation efficiency of E. cloni EXPRESS Electrocompetent Cells (> 5 × 109 cfu/µg) eliminates the need for plasmid transfer from the cloning strain to the expression strain, saving days of work in a typical cloning and expression experiment (Figure. 2).
Figure 1. Transformation efficiency comparison of commercially available BL21(DE3) competent cells.
Figure 2. Comparison of cloning and protein expression procedures.
E. cloni EXPRESS BL21(DE3) strains contain the phage T7 RNA polymerase gene linked to the IPTG-inducible promoter, for use with any expression plasmid containing the T7 promoter.
NOTE: For best results in expressing proteins that may be toxic, we recommend using OverExpress Cells. E. cloni EXPRESS cells are also available as chemically competent cells. With a transformation efficiency of >1 × 107 cfu/µg and very economical prices, EXPRESS Chemically Competent Cells offer superior value for everyday protein expression work.
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Key features
Best value for routine protein expression
Available as Electrocompetent and Chemically Competent Cells.
Specifications
Genotype
E. cloni EXPRESS BL21(DE3): F– ompT hsdSB (rB- mB-) gal dcm lon λ(DE3 [lacI lacUV5-T7 gene 1 ind1 sam7 nin5])
Product Details
Each E. cloni EXPRESS Kit contains: the indicated E. cloni EXPRESS Electrocompetent or Chemically Competent Cells in DUO packaging (2 transformations per tube), Expression Recovery Medium (lactose minus), pUC19 Positive Control Plasmid, and complete protocols.
