DH5-Alpha Cells are E.coli cells engineered to maximize transformation efficiency. They are defined by three mutations recA1, endA1 which help plasmid insertion and lacZM15 which enable blue white screening. The cells are competent and often used with calcium chloride transformation to insert the desired plasmid. A study of four transformation methods and six bacteria strains showed that the most efficient one was the DH5 strain with the Hanahan method
- The recA1 mutation is a single point mutation that replaces glycine 160 of the recA polypeptide with an aspartic acid residue in order to disable the activity of the recombinases and inactivate homologous recombination.
- The endA1 mutation inactivates an intracellular endonuclease to prevent it from degrading the inserted plasmid.
- "Strain - DH5α". cgsc2.biology.yale.edu. Retrieved 2017-05-23.
- Chan, Weng-Tat; Verma, Chandra S.; Lane, David P.; Gan, Samuel Ken-En (2013-12-12). "A comparison and optimization of methods and factors affecting the transformation of Escherichia coli". Bioscience Reports. 33 (6). doi:10.1042/BSR20130098. ISSN 0144-8463. PMC 3860579. PMID 24229075.
- Bryant, Floyd (November 9, 1987). "Construction of a Recombinase-deficient Mutant recA Protein That Retains Single-stranded DNA-dependent ATPase Activity" (PDF). Journal of Biological Chemistry.