Hot-start Taq enzyme is a thermostable DNA polymerase isolated from Thermus Aquaticus (Taq). Commonly used Taq enzymes can be divided into two categories: rTaq enzymes and LTaq enzymes. LTaq enzymes have stronger fidelity and better heat resistance than rTaq enzymes.

It is a milestone for the application of PCR. The PCR cycle includes denaturation (about 90 °C), annealing (about 50 °C), and extension (about 70 °C). Each step has different temperature requirements. However, the enzyme can withstand high temperatures above 90 °C without inactivation, so it is not necessary to add enzymes for each cycle, making the PCR technology very simple. At the same time, the cost has been greatly reduced, and PCR technology has been widely used and gradually applied in clinical practice.

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When using Taq DNA polymerase for PCR reaction, denaturation is often carried out at 94~95°C, which is also tolerated when Taq DNA polymerase performs 30 or more PCR cycles without excessive loss of activity. of high temperature. However, the fidelity of this enzyme is not high because the DNA polymerization of this enzyme relies on 3'-5' correction.

Different from general enzymes, when DNA is amplified by Taq enzyme, an A is protruded from the 3' end of the fragment, which should be noted. This is because Taq DNA polymerase has a template-independent terminal transferase activity (extension activity), which leads to amplification DNA fragments are appended with a single unpaired nucleotide at the 3' end.