Denaturation optimal thermal processing

The most widely used DNA polymerase in PCR is from Thermus acquaticus, the Taq polymerase. This enzyme has an optimal temperature for polymerization in the range of 70 to 75°C. It extends DNA chains at a rate of about 2 kb per minute. It is fairly resistant to the continual cycles of heating and cooling required for PCR. The half-life for thermal denaturation of Taq polymerase is 1.6h at 95°C. When very high denaturation temperatures are needed, as in the PCR amplification of very G+C-rich DNA, more thermal-stable polymerase such as the enzyme from Thermococcus litoralis with a half-life of 1.8h at 100°C or the enzyme from Pyrococcus furiosis with a half-life of 8 h at 100°C, can be employed. However, these enzymes are not as processive as Taq polymerase, which makes it more difficult to amplify long templates. 

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