Taq polymerase (pronounced; tack poll-im-er-aze) is a thermostable DNA polymerase named after the thermophilic bacterium Thermus aquaticus from which it was originally isolated by Thomas D. Brock in 1965[1]. It is often abbreviated to "Taq Pol" (or simply "Taq"), and is frequently used in polymerase chain reaction (PCR), methods for greatly amplifying short segments of DNA.
T. aquaticus is a bacterium that lives in hot springs and hydrothermal vents, and Taq polymerase was identified[1] as an enzyme able to withstand the protein-denaturing conditions (high temperature) required during PCR[2]. Therefore it replaced the DNA polymerase from E.coli originally used in PCR [3]. Taq's optimum temperature for activity is 75-80°C, with a halflife of 9 minutes at 97.5°C, and can replicate a 1000 base pair strand of DNA in less than 10 seconds at 72°C[4].
One of Taq's drawbacks is its relatively low replication fidelity. It lacks a 3' to 5' exonuclease proofreading activity[4], and has an error rate measured at about 1 in 9,000 nucleotides[5]. Some thermostable DNA polymerases have been isolated from other thermophilic bacteria and archaea, such as Pfu DNA polymerase, possessing a proofreading activity, and are being used instead of (or in combination with) Taq for high-fidelity amplification.
Taq makes DNA products that have A (adenine) overhangs at their 3' ends. This may be useful in TA Cloning, whereby a cloning vector (such as a plasmid) is used which has a T (thymine) 3' overhang, which complements with the A overhang of the PCR product, thus enabling ligation of the PCR product into the plasmid vector.
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http://qjmed.oxfordjournals.org/cgi/reprint/78/3-4/195