TFB 10B™
TFB 10B™ Competent Cells are chemically competent E. coli cells and are intended to be transformed by heat-shock. The high transformation efficiency of these cells makes them ideally suited for demanding applications such as cDNA or genomic library construction.
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| Recommended Use | cDNA or genomic library construction, cloning of methylated DNA. |
| Efficiency | ≥ 10^9 cfu / µg |
| Shipping | Dry ice |
| Genotype | F- mcrA Δ(mrr-hsdRMS-mcrBC) Φ80dlacZΔM15 ΔlacX74 recA1 endA1 hsdR araD139 Δ(ara leu)7697 galU galK rpsL nupG λ- fhuA (T1R). |
TFB 10B™ Competent Cells are chemically competent E. coli cells and are intended to be transformed by heat-shock. The high transformation efficiency of these cells makes them ideally suited for demanding applications such as cDNA or genomic library construction (1).
TFB 10B™ cells are resistant to bacteriophage T1, an especially virulent virus which attacks E. coli, and can be rapidly spread via aerosols.
Handling and Storage
- Upon receipt, store cells immediately at -70°C or below.
- Competent cells should be thawed on wet ice (~ 10 minutes) and should be used promptly after thawing.
- Thawed cells can be refrozen by placing them in dry ice although a drop in transformation efficiency of as much as ≥ 50% may be observed. Cells stored properly will remain stable for up to 2 years.
Kit Contents
- TFB 10B™ Competent Cells
- pUC19 Control DNA (10 pg / µl)
Genotype
F- mcrA Δ(mrr-hsdRMS-mcrBC) Φ80dlacZΔM15 ΔlacX74 recA1 endA1 hsdR araD139 Δ(ara leu)7697 galU galK rpsL nupG λ- fhuA (T1R).
Note: The Δ(mrr-hsdRMS-mcrBC) deletion, together with the mcrA mutation, allow cloning of methylated DNA such as genomic DNA from eukaryotic sources.
Quality Control
TFB 10B™ cells are tested to verify transformation efficiencies of ≥ 1 x 109 transformants/µg with limiting amounts of supercoiled pUC19 DNA (50 pg) and ≥ 1 x 106 cfu's per 100 ul transformation when using 25 ng of pUC19 (i.e., "saturating amounts"). Untransformed cells are also tested for resistance to bacteriophage T5, a standard test for resistance to phage T1, as well as other relevant genetic markers and sensitivities to antibiotics.
Considerations in Choosing Competent Cells
Key Genetic Markers:
- recA - eliminates homologous recombination; stabilizes inserts.
- endA - endonuclease deficiency improves yield and quality of plasmid DNA.
- hsd - classical restriction/modification system, deficiency allows cloning from non-E. coli sources, e.g. PCR products.
- F’ - episome required for infection by M13 and other phagemids. Important in generation of ssDNA.
- mcrA, mcrBC, mrr - mutations in these genes allows efficient cloning of genomic from mammalian or other higher eucaryotes, and methylated cDNA.
- lacZΔM15 - omega donor; allows a-complementation for blue/white screening.
Product Selection Guide:
