Taq polymerase

An enzyme used in PCR to amplify DNA sequences

Overview

Taq polymerase is a thermostable DNA polymerase named after the thermophilic bacterium Thermus aquaticus from which it was originally isolated. This enzyme is a key component in the polymerase chain reaction (PCR), a technique widely used in molecular biology to amplify segments of DNA.

Discovery and Properties

Taq polymerase was discovered in the 1960s in the hot springs of Yellowstone National Park. Its ability to withstand the high temperatures required for PCR makes it invaluable in biotechnology. Unlike other DNA polymerases, Taq polymerase remains stable and active at temperatures up to 95°C, which is necessary for the denaturation step in PCR.

Function in PCR

Taq polymerase structure

In PCR, Taq polymerase synthesizes a new DNA strand by adding nucleotides to a primer annealed to a template DNA strand. The enzyme's optimal activity occurs at around 75-80°C, which is the temperature used during the extension phase of PCR. Taq polymerase lacks 3' to 5' exonuclease activity, meaning it does not have proofreading ability, which can lead to errors in the amplified DNA.

Applications

Taq polymerase is used in various applications beyond PCR, including DNA sequencing, cloning, and genotyping. Its robustness and efficiency make it a staple in laboratories worldwide.

Limitations

Despite its widespread use, Taq polymerase has limitations, such as its lack of proofreading ability, which can result in a higher error rate compared to other polymerases with proofreading functions. This can be a concern in applications requiring high fidelity.

Related pages

• Polymerase chain reaction
• DNA polymerase
• Thermus aquaticus
• Molecular biology