Taq polymerase

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Taq polymerase is an enzyme found in Thermus aquaticus, an organism which live in environments of extremely high temperatures, such as hot springs. It is therefore extremely thermostable, hence known as thermophilic bacterium. The enzyme is commonly used in Polymerase Chain Reaction (PCR) as it can withstand the required high temperatures (95 degrees celsius)[1] of the Thermo Cycler, while retaining its enzymatic functions. Taq polymerase is homologous to DNA polymerase in Escherichia Coli, which is Polymerase I. [2]

During PCR, Taq polymerase is used to extend the primers by adding the nucleotide to the template. This is due to the fact that during PCR the reactants are heated to 95°C and normal DNA Polymerase III would be denatured by this high temperature.The optimum temperature for the Taq polymerase is 75-80 degree Celsius. Moreover, Taq polymerase has an error rate of approximately one in every million base pairs and thus, Pfu, another thermostable DNA polymerase may instead be used in PCR. It has a proof reading ability and is, therefore, more accurate [3]. DNA Taq polymerase can also stand at a temperature of 37 degrees for 7 days without losing its activity. It has a terminal transferase activity involving adding of a nucleotide one at a time to the 3' end; however, it should be noted that this enzyme has an error rate of approximately one in every million base pairs [4].

The molecular weight of taq polymerase is estimated to be 63,000 - 68,000 Da, this was calculated using molecular techniques such as sucrose gradient centrifugation and gel filtrations on Sephadex G-100[5].

References

  1. http://biotechcrunch.blogspot.co.uk/2011/06/taq-polymerase-enzyme.html
  2. 1TAQ: Structure Of Taq Dna Polymerase - NCBI structure. (n.d.). Retrieved October 18, 2017, from https://www.ncbi.nlm.nih.gov/Structure/pdb/1TAQ
  3. Methods Mol Biol. 2011;682:65-75.
  4. http://taqpolymerase.net/
  5. J Bacteriol. 1976 Sep; 127(3): 1550–1557
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