Taq polymerase

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 polymerase chain reaction (PCR), a widely used laboratory technique for amplifying DNA sequences.

History

The discovery of Taq polymerase was a significant breakthrough in the field of molecular biology. The enzyme was first isolated from Thermus aquaticus, a bacterium that thrives in hot springs, in the late 1960s. However, its potential for use in PCR was not realized until the 1980s.

Characteristics

Taq polymerase is a thermostable enzyme, meaning it can withstand high temperatures without losing its functionality. This property makes it ideal for use in PCR, which involves repeated cycles of high-temperature heating and cooling. Taq polymerase has a temperature optimum of approximately 75-80°C, and can remain active even after incubation at 95°C for several hours.

Role in PCR

In PCR, Taq polymerase synthesizes new strands of DNA from a DNA template and primers. The enzyme adds nucleotides to the 3' end of the primer, extending the DNA strand. Because Taq polymerase is thermostable, it can survive the high temperatures used in PCR to separate the DNA strands, eliminating the need to add fresh enzyme after each cycle.

Limitations

While Taq polymerase has revolutionized molecular biology, it is not without its limitations. The enzyme lacks proofreading activity, which means it can introduce errors into the DNA sequence during amplification. This can be a problem in applications where accuracy is critical, such as DNA sequencing and genotyping.

See also

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