Competent Cells for Large or Ligated DNA - Details & Specifications

Ligated plasmid DNA generally transforms with significantly lower efficiency than supercoiled plasmids, and large plasmids transform less efficiently than small plasmids. This bias against transformation of larger constructs impacts the construction of plasmid libraries and reduces the probability of finding full-length cDNA clones.

XL10-Gold Ultracompetent Cells

XL10-Gold Ultracompetent Cells were created for transformation of large DNA molecules with high efficiency (see Figure 1). These cells exhibit the Hte phenotype, which increases the transformation efficiency of ligated and large DNA molecules. XL10-Gold ultracompetent cells are ideal for constructing plasmid DNA libraries because they decrease size bias and produce larger, more complex plasmid libraries. XL10-Gold cells are deficient in all known restriction systems. The strain is endonuclease deficient (endA), greatly improving the quality of miniprep DNA, and recombination deficient (recA), helping to ensure insert stability. Blue-white screening for recombinant plasmids.

Efficiency: ≥5 x 10⁹ transformants/µg of pUC18 DNA
<Resistant to tetracycline and chloramphenicol.

Figure 1. Transformation of cDNA Libraries. A mouse brain cDNA library was prepared using our cDNA Synthesis Kit, then was ligated to EcoR I- and Xho I- digested pCMV-Script vector (4.2 kb). 1 µl aliquots of the ligation reaction were used to transform 100 µl of DH10B, XL2-Blue and XL10-Gold competent cells according to the manufacturers' protocols. The identical experiment was also performed with the 7.2 kb pAD-GAL4 vector. For the transformation control, supercoiled pUC18 was used.

XL10-Gold Kan^r Ultracompetent Cells

XL10-Gold Kanr cells are identical to XL10-Gold cells except that XL10-Gold Kan^r cells harbor a kanamycin-resistance gene on the F' episome rather than a chloramphenicol-resistance gene. XL10-Gold Kan^r cells are ideal when using vectors that encode chloramphenicol resistance.

Efficiency: ≥5 x 10⁹ transformants/µg of pUC18 DNA
Resistant to tetracycline and kanamycin.

ElectroTen-Blue Electrocompetent Cells

The ElectroTen-Blue Electroporation Competent Cells are a derivative of the XL1-Blue MRF´ strain that can withstand much higher levels of electrical current. This increases the survival of the cells, and thus the efficiency of transformation by ligated constructs. In addition the ElectroTen-Blue strain is deficient in all known restriction systems and is endonuclease deficient (endA1) and recombination deficient (recA1). Therefore, it is an excellent strain for constructing genomic or DNA libraries using methylated cDNAs. The lacIqZΔM15 gene on the F´ episome allows blue-white color selection of recombinants if the cells are transformed with a plasmid capable of complementing the deletion in the ß-galactosidase gene of the bacterial cell.

Efficiency: ≥3 x 10¹⁰ transformants/µg of pUC18 DNA
Resistant to tetracycline and kanamycin.

For Research Use Only. Not for use in diagnostic procedures