More of Your Recombinant Proteins
- Less Background
BL21 Gen-X™
E.coli is a new generation of BL21(DE3) that provides significantly higher levels of recombinant protein expression
and significantly reduced levels of background protein levels compared to previous versions of BL21(DE3).
BL21 Gen-X™ Features:
- Up to 10X greater expression of your recombinant proteins
- Reduced background protein levels, as much as several fold
- Detect proteins not visible if expressed in other BL21 strains
- Simple and straightforward protocol
- Compatible with all T7 promoter-based expression vectors
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Figure 1. Comparison of protein expression from pET vectors in BL21 Gen-X™ and standard BL21 (DE3) E. coli cells.
Ten 2 ml cultures of BL21 (DE3) each containing a different protein expression construct were grown at 37oC in LB and induced with 1 mM IPTG at OD600 = 0.4.
Cells were incubated overnight and 1 ml harvested. Concurrently, 2 ml cultures of BL21 Gen-X™ containing the same ten protein expression
constructs were grown at 37oC in M9 minimal media and induced with 1 mM IPTG at the same OD. Cells were incubated overnight and
1ml harvested. For both strains, pellets were suspended in 100ul, lysed, and 10ul electrophoresed on 4-12% polyacrylamide gels. In lanes
1,3,4,5,6,8,9, and 10, the quantity of recombinant protein obtained from BL21 Gen-X™ cells was considerably greater and the background
of endogenous E. coli proteins significantly lower
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The BL21 Gen-X™ cells were created through careful cycles of
mutagenesis, enrichment, and testing, resulting in a novel and more
powerful protein expression strain. By reducing the growth rate and
optimizing other characteristics, Genlantis scientists have produced
BL21(DE3) cells that are qualitatively distinct from previous
generations of BL21(DE3) E. coli.
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Figure 2. Comparison of protein expression from pET vectors in BL21 Gen-X™ E. coli with and without addition of the Gen-X Induction
Enhancer. Cells were grown and induced as described in Figure 1. Additionally, 220ul of the 10X Gen-X™ Induction Enhancer were
added at the time of IPTG addition; downstream processing was the same. For many constructs, the addition of the Gen-X™
Induction Enhancer noticeably reduced background protein expression. This is because the Gen-X™ Induction Enhancer further
reduces the growth rate of the cells. In some instances, there is a decrease in absolute recombinant protein expression.
However, the net result is a protein yield of higher purity due to the relatively lower background. In other cases, the
Gen-X™ Induction Enhancer is essential for abundant target protein expression; for example in Lane 2, the 60KDa recombinant
protein was observed only in the BL21 Gen-X™ cells along with the Gen-X™ Induction Enhancer, while in lane 8, the induction
enhancer was responsible for increased expression of the 69 KDa protein. |
The results are striking: BL21 Gen-X™, along with the powerful Gen-X™ Induction Enhancer, will express more of what you want, and less
of what you don't want. For example, the BL21 Gen-X™ cells are able to express proteins that are not expressed or detected at all using
other popular BL21 cells or kits. (see Figure 2, lanes 2) With the BL21 Gen-X™ Competent E. coli Expression Kit, there is now a
better way to express your recombinant proteins. The resulting higher yields and lower background will make downstream purification and
processing of your recombinant proteins much easier, saving you significant time and money.