Taq DNA Polymerase

  • Isolated from the thermophilic bacterium Thermus aquaticus
  • Thermostable DNA polymerase
  • Catalyzes 5’→3′ DNA synthesis (5’→3′ polymerase activity) from primed single-stranded DNA in the presence of Mg2+
  • Possesses low 5’→3′ exonuclease activity
  • Lacks 3′→5′ exonuclease activity (proofreading)
  • Exhibits deoxynucleotidyl transferase activity (addition of extra adenines at the 3′-end of PCR products)
  • Error rate: 1 × 10–5 errors/base
  • Extension rate: >60 nucleotides/second at 70°C (Innis et al., 1988)
  • Half life at 95°C: 40 minutes


  • Frequently used for polymerase chain reaction, suitable for PCR reactions that do not require high-fidelity enzymes, frequently used for the amplification of upto 5 kb DNA fragment
  • DNA labeling (Oligo probe preparation)


  • Innis et al., 1988. DNA sequencing with Thermus aquaticus DNA polymerase and direct sequencing of polymerase chain reaction-amplified DNA. Proc Natl Acad Sci U S A. 85(24), 9436-9440. PMID-3200828; Full Text Links: pnas (download PDF), PMC282767
  • Lawyer et al., 1993. High-level expression, purification, and enzymatic characterization of full-length Thermus aquaticus DNA polymerase and a truncated form deficient in 5′ to 3′ exonuclease activity. PCR Methods Appl. 2(4), 275-287. PMID-8324500; Full Text Link: cshlp (download PDF)

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