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lucigen OverExpress™ C43 (DE3) pLysS Chemically Competent Cells</p>
产品简介：北京中北林格供应lucigen 60448-2 OverExpress™ C43 (DE3) pLysS Chemically Competent Cells，中北林格是lucigen总代理，提供lucigen产品货号报价查询。代理的其他品牌包括Biosearch technologies总代理，epicentre总代理，illumina总代理，ICLLAB总代理，ImmunoReagents总代理。</p>
产品名称：OverExpress™ C43 (DE3) pLysSChemically Competent Cells</p>
货号：lucigen 60448-2</p>
规格：24 rxns (SOLOs)</p>
存储温度：-80º C</p>
品牌：lucigen</p>
供应商：中北林格</p>
产地：us</p>
发货地：北京</p>
E. coli BL21(DE3) strains, like Lucigen’s E. cloni® EXPRESS Competent Cells provide reliable expression of many genes cloned into T7 expression vectors (e.g., pET or Lucigen’s pSMART®-cDNA vectors). However, in some cases expression is minimal or not detectable because the recombinant protein, when expressed, is deleterious or lethal to these standard BL21 strains. Examples of such toxic proteins include many membrane proteins, some cytoplasmic proteins, ａnd nucleases. Unfortunately, successful expression of one or more toxic proteins is often important to the experimental goal.
Lucigen’s OverExpress Electrocompetent ａnd Chemically Competent Cells are E. coli strains that are effective in expressing toxic proteins from all classes of organisms, including eubacteria, yeasts, plants, viruses, ａnd mammals. The effectiveness of these new strains in expressing toxic proteins has been validated in more than 350 publications.
The OverExpress strains contain genetic mutations phenotypically selected for conferring tolerance to toxic proteins. The strain C41(DE3) was derived from BL21(DE3). This strain has at least one mutation, which prevents cell death associated with expression of many recombinant toxic proteins. The strain C43(DE3) was derived from C41(DE3) by selecting for resistance to a different toxic protein ａnd can express a different set of toxic proteins to C41(DE3). Figure 1 graphically illustrates the advantages of the OverExpress Competent Cells, compared to standard BL21(DE3) cells, in expressing toxic proteins.
| Figure 1. Green Fluorescent Protein (top) or Red Fluorescent Protein (bottom) expressed from a T7 promoter construct that was transformed into C41, BL21, or C43 competent cells spread on IPTG plates to induce protein expression. |
Table 1 ａnd Figure 2 summarize transformation effectiveness, tolerance of expression-induced toxicity, ａnd protein expression for T7 expression plasmids coding for a variety of recombinant proteins. These results demonstrate that the OverExpress C41(DE3) ａnd C43(DE3) strains are clearly superior to the parental BL21(DE3) in transformation ａnd expression of toxic proteins.
Table 1. Comparison of OverExpress C41(DE3) ａnd C43(DE3) cells with the parental strain BL21(DE3) in transformation ａnd expression of heterologous proteins.**
| Strain | Transformation Success Ratea | Expression-induced Toxicityb | Expressing Plasmidsc |
| BL21(DE3) | 16/26 (62%) | 25/26 (96%) | 14/26 (54%) |
| C41(DE3) | 28/28 (100%) | 14/28 (50%) | 24/28 (86%) |
| C43(DE3) | 28/28 (100%) | 1/28 (4%) | 23/28 (81%) |
| Figure 2. Comparison of OverExpress C41(DE3) ａnd C43(DE3) cells with the parental strain BL21(DE3) in transformation ａnd expression of heterologous proteins.** |
a Transformation success corresponds to the presence of colonies on LB+ampicillin agar following transformation with a plasmid.
b Expression toxicity corresponds to the absence of colonies on LB+ampicillin+IPTG agar following transformation with a plasmid.
c Expressing plasmids corresponds to observation of a heterologous protein in the total cell pellet on Coomassie-stained SDS-PAGE following growth of a colony in LB+ampicillin medium ａnd induction with IPTG.
**L. Dumon-Seignovert, G. Cariot, ａnd L. Vuillard (2004). Protein Expression ａnd Purification 37, 203-206. Data used with permission.
As in standard BL21(DE3) strains, OverExpress C41(DE3), C41(DE3)pLysS, C43(DE3), ａnd C43 (DE3)pLysS are lysogens of λDE3. These strains carry a chromosomal copy of the T7 RNA Polymerase gene under the control of thelacUV5 promoter. These strains are suitable for production of protein from target genes cloned into T7-driven expression vectors. OverExpress C41(DE3), C41(DE3) pLysS, C43(DE3), ａnd C43(DE3) pLysS are also deficient in the lon ａnd ompT proteases.
OverExpress C41(DE3)pLysS ａnd C43(DE3)pLysS also carry a chloramphenicol-resistant plasmid that encodes T7 lysozyme, which is a natural inhibitor of T7 RNA polymerase. Cells containing pLysS produce a small amount of T7 lysozyme. These strains are used to suppress basal expression of T7 RNA polymerase prior to induction, thus stabilizing recombinants encoding particularly toxic proteins.
It is difficult to predict which of the four OverExpress strains – C41(DE3), C43(DE3), C41(DE3)pLysS, or C43(DE3)pLysS – will work best in expressing a given protein. We recommend initially using the OverExpress ComboPack™ which contains 3 reactions each of the four OverExpress competent cell strains, to determine which one is best for your application. The OverExpress strains are available as electrocompetent or chemically competent cells.
Because there are no intrinsic antibiotic resistances (or plasmids) in either C41(DE3) or C43(DE3), the strains can be differentiated from each other ａnd from BL21(DE3) by transformation with a strain verification vector, pAVD10. pAVD10 contains the uncF gene (encoding the beta-subunit of E. coli ATPase) under the control of the T7 promoter. This plasmid is lethal to BL21(DE3) ａnd to induced C41(DE3), but it is tolerated by C43(DE3) regardless of induction. pAVD10 is provided with OverExpress Cells.
| Product Description | Size | Cat. No. | |
| OverExpress C41(DE3) Chemically Competent Cells | 12 rxns (SOLOs) | 60442-1 | |
| 24 rxns (SOLOs) | 60442-2 | ||
| OverExpress C41(DE3) pLysS Chemically Competent Cells | 12 rxns (SOLOs) | 60444-1 | |
| 24 rxns (SOLOs) | 60444-2 | ||
| OverExpress C43(DE3) Chemically Competent Cells | 12 rxns (SOLOs) | 60446-1 | |
| 24 rxns (SOLOs) | 60446-2 | ||
| OverExpress C43(DE3) pLysS Chemically Competent Cells | 12 rxns (SOLOs) | 60448-1 | |
| 24 rxns (SOLOs) | 60448-2 | ||
| OverExpress ChemComboPack (3 rxns each of the above four strains) | 12 rxns (SOLOs) | 60452-1 | |
| OverExpress C41(DE3) Electrocompetent Cells | 12 rxns (SOLOs) | 60341-1 | |
| 24 rxns (SOLOs) | 60341-2 | ||
| OverExpress C43(DE3) Electrocompetent Cells | 12 rxns (SOLOs) | 60345-1 | |
| 24 rxns (SOLOs) | 60345-2 | ||
| Expression Recovery Medium (lactose minus) | 8 × 12 ml | 80030-1 | |
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