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Merck
CN

J3895

Sigma-Aldrich

JM109 Competent Cells

for routine DNA plasmid production

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About This Item

UNSPSC Code:
12352200

Key Documents

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Technical Service
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grade

Molecular Biology

form

suspension

cell transformation

competent cell type: chemically competent
transformation efficiency: >1 x 108 cfu/μg

shipped in

dry ice

storage temp.

−70°C

General description

JM109 are competent E. coli with a transformation efficiency of >1x108 cfu/μg when transformed with non-saturating amounts of pUC19 plasmid DNA.

Application

Suitable for bacterial transformations to recover high quality plasmid DNA or single-stranded bacteriophage DNA

Biochem/physiol Actions

JM109 competent E. coli contains mutations in recA1 and endA1 genes. These mutations aid in minimizing recombination and ensuring plasmid stability. The F′ factor is suitable for the growth of bacteriophages (such as M13) to obtain single stranded DNA.

Features and Benefits

  • Ensures recovery of stable and high quality plasmid DNA
  • Guaranteed high transformation efficiency
  • Convenient pack size is sufficient for 10 transformation reactions

Other Notes

  • JM109 chemically competent cells, 10 X 50 μL (J4020)
  • pUC 19 control DNA (10 ng/μL), 10 μL (D2567)

Storage Class Code

10 - Combustible liquids

Regulatory Information

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Certificates of Analysis (COA)

Lot/Batch Number
SLBL8705V
SLBK9435V
SLBK5846V
SLBJ1211V
SLBH2932

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  1. Which document(s) contains shelf-life or expiration date information for a given product?

    If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.

  2. How do I get lot-specific information or a Certificate of Analysis?

    The lot specific COA document can be found by entering the lot number above under the "Documents" section.

  3. How do I find price and availability?

    There are several ways to find pricing and availability for our products. Once you log onto our website, you will find the price and availability displayed on the product detail page. You can contact any of our Customer Sales and Service offices to receive a quote.  USA customers:  1-800-325-3010 or view local office numbers.

  4. What is the Department of Transportation shipping information for this product?

    Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product. 

  5. Are home-made competent cells as efficient at transformation as purchased cells?

    They can be, depending on the technique used, the expected transformation efficiency and how the cells are handled.  For special applications, competent cells prepared in-house using standard methods may not provide the efficiency you need.

  6. Are all competent cells suitable for both plasmid production and protein expression?

    No.  Most strains of competent cells are suitable for producing plasmid DNA that will be used to transfect insect or mammalian cells for expression of the protein.  The BL21 competent cell strains have special traits enabling protein expression in bacteria.

  7. What are important considerations when performing bacterial transformation?

    Things to consider when planning bacterial transformation:DNA impuritiesSource of DNAAmount of DNA usedStorage and handling of the competent cells

  8. Can I store the competent cells in the -20C?

    No.  Competent cells should not be stored at -20C for any length of time.  The cells suffer a dramatic drop in transformation efficiency when stored higher than -80C.

  9. How should I thaw the competent cells?

    Competent cells should be thawed on ice.  The transformation efficiency is dependent on the proper handling of the cells (maintaining cold temperature until transformation).

  10. Can I re-freeze the vial if I do not use the entire aliquot of competent cells?

    Re-freezing competent cells will result in a decrease in their transformation efficiency.  If the cells are frozen first in a dry ice / ethanol bath before placement in the -80C freezer, the loss will be about two-fold.  If placed directly in the -80C freezer, the loss in transformation efficiency is about five to ten-fold.

  11. Competent cells were left on ice overnight - can they still be used?

    Competent cells left on ice, or allowed to come to room temperature slowly will suffer a dramatic loss in transformation efficiency.  We recommend thawing a new aliquot of competent cells.

  12. Can I express a recombinant protein that is toxic to the bacteria?

    For expression of toxic recombinant proteins, select the BL21 strain containing the pLysS plasmid. These cells express low levels of lysozyme that will bind to T7 polymerase, and inhibit transcription.  

  13. What DNA purity do I need for use in transformation?

    The DNA used should be high quality - free from phenol, proteins, detergents, and ethanol.  Dissolve the DNA in sterile water or 0.5x TE buffer (5 mM Tris-HCl, 0.5 mM EDTA).

  14. Can I grow more competent cells from the stock I purchased?

    Generally, no, because the future generations of cells lose their competency.

  15. My question is not addressed here, how can I contact Technical Service for assistance?

    Ask a Scientist here.

Katherine McCaffrey et al.
PloS one, 6(8), e23213-e23213 (2011-08-10)
The highly conserved members of the zic family of zinc-finger transcription factors are primarily known for their roles in embryonic signaling pathways and regulation of cellular proliferation and differentiation. This study describes sexual phenotype differences in abundances of zic2 mRNA
C Yanisch-Perron et al.
Gene, 33(1), 103-119 (1985-01-01)
Three kinds of improvements have been introduced into the M13-based cloning systems. (1) New Escherichia coli host strains have been constructed for the E. coli bacteriophage M13 and the high-copy-number pUC-plasmid cloning vectors. Mutations introduced into these strains improve cloning
Gillian G Johnson et al.
Cancer research, 69(12), 5210-5217 (2009-06-06)
The ATM-p53 pathway plays an important role in the biology of chronic lymphocytic leukemia (CLL). Its functional integrity can be probed by exposing CLL cells to ionizing radiation (IR) and measuring levels of p53 protein and one of its transcriptional

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