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Abstract for E. coli Competent Cells
Promega E. coli Competent Cells are prepared according to a
modified procedure of Hanahan. The competent cells can be used for many standard
molecular biology applications. Competent cells of strains HB101 and JM109 are
available for convenient transformation in two efficiencies: High Efficiency at
greater than 108cfu/µg and Subcloning Efficiency at greater than 107cfu/µg.
JM109 cells are an ideal host for many molecular biology applications. HB101
cells are useful for cloning in vectors that do not require
alpha-complementation for blue/white screening. The BMH 71-18 mutS
strain is suitable for use in in vitro mutagenesis procedures where a repair
(–) strain is required. BL21(DE3)pLysS cells can be used with protein
expression vectors that are under the control of the T7 promoter, such as pET
vectors. This strain is lysogenic for lambda-DE3, which contains the T7
bacteriophage gene 1, encoding T7 RNA polymerase under the control of the lacUV5
promoter. BL21(DE3)pLysS also contains the pLysS plasmid, which carries the gene
encoding T7 lysozyme. T7 lysozyme lowers the background expression level of
target genes under the control of the T7 promoter but does not interfere with
the level of expression achieved following induction with IPTG.
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