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E. cloni® EXPRESS Competent Cells

Best value for routine protein expression...
available as Electrocompetent and Chemically Competent Cells.

EXPRESS BL21(DE3), BL21(DE3)pLysS, BL21(DE3)pLysE

Lucigen’s 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 x 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.

EXPRESS pLysS Electrocompetent Cells (> 2 x 108 cfu/µg) also produce T7 lysozyme to repress low-level transcription from the T7 promoter prior to IPTG induction, helping to stabilize inserts coding for deleterious products. EXPRESS pLysE Electrocompetent Cells > 2 x 108 cfu/µg) have a higher level of repression by T7 lysozyme, offering the greatest control over expression of inserts. The ComboPack™ contains 4 transformations each of the E. cloni EXPRESS Competent Cell strains, to determine which works best in expressing your protein of interest.

NOTE: For best results in expressing proteins that may be toxic, we recommend using OverExpress Cells™ instead of EXPRESS pLysS or pLysE strains.

All three E. cloni EXPRESS strains are also available as chemically competent cells. With a transformation efficiency of > 1 x 107 cfu/µg and very economical prices, EXPRESS Chemically Competent Cells offer superior value for everyday protein expression work.

E. cloni EXPRESS Genotypes
EXPRESS BL21(DE3): F– ompT hsdSB (rB- mB-) gal dcm (DE3)
EXPRESS BL21(DE3)pLysS: F– ompT hsdSB (rB- mB-) gal dcm (DE3) pLysS (CmR)
EXPRESS BL21(DE3)pLysE: F– ompT hsdSB (rB- mB-) gal dcm (DE3) pLysE (CmR)

E. cloni EXPRESS Kit Manuals
EXPRESS Chemically Competent Cell Manual
 EXPRESS Electrocompetent Cell Manual

Important Product Use Information
E. cloni EXPRESS Cells are sold under a license issued to Lucigen Corporation by Brookhaven Science Associates, LLC (BSA) for research use by noncommercial entities. Commercial entities require a license from BSA even for research use.

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