Taq Polymerase

Taq DNA polymerase, isolated from Thermus aquaticus, is a thermostable DNA polymerase that catalyzes the primer-dependent incorporation of nucleotides into duplex DNA in the 5′→3′ direction in the presence of Mg²⁺. It is the standard thermostable DNA polymerase used in PCR applications. Taq does not possess 3′→5′ exonuclease activity but has 5′→3′ exonuclease activity. Taq polymerase is suitable for most PCR applications that do not require a high-fidelity enzyme, such as detecting specific DNA or RNA sequences. 

A typical polymerase chain reaction (PCR) includes target DNA, a thermostable DNA polymerase such as Taq polymerase, two oligonucleotide primers, dNTPs, reaction buffer and magnesium. Once assembled, the reaction is placed in a thermal cycler, which subjects the reaction to recurring cycles of temperature changes during which the DNA is denatured, primers anneal to the target and are extended by the polymerase to create a copy of the DNA strand. Each PCR cycle theoretically doubles the amount of targeted sequence in the reaction until the reaction components become limiting or are consumed. 

In endpoint PCR, analysis occurs after all cycles of PCR are completed and the amplification reaction has reached a plateau (or endpoint). This contrasts with real-time qPCR, where PCR product formation is monitored in real time as the amplification reaction occurs. Endpoint PCR is a qualitative method. It is widely used for many purposes including determining the presence or absence of a specific DNA sequence in a target sample, detecting pathogens, amplifying target sequences for further analysis, and detecting specific DNA sequences in order to identify individuals or cell types. 

PCR Master Mixes contain all the reaction components for PCR, including Taq polymerase, dNTPs and optimized buffer. Master mixes simplify experimental setup and save time, as the user simply needs to add template and primers to the reaction.