Polymerase Chain Reaction, Common PCR Enzymes

PCR (polymerase chain reaction) is a technique commonly used to amplify DNA molecules in vitro, and PCR enzymes are a key component of this reaction. The main types of PCR enzymes include Taq polymerase, Pfu polymerase, and hot-start variants of Taq DNA polymerase.

Taq polymerase

Taq polymerase was one of the first PCR enzymes to be widely used. It was isolated from a bacterium known as Thermus aquaticus and has excellent heat resistance. Taq polymerase is stable at high temperatures and is suitable for denaturation, annealing, and extension steps of PCR. However, Taq polymerase suffers a high error rate in regions with high GC content because it lacks the 3′-5′ exonucleation correction function.

Pfu Polymerase

Pfu polymerase is isolated from thermophilic cyanobacteria and is superior in heat resistance compared to Taq polymerase. It has a 3′-5′ exonucleotide correction function, so it has a lower error rate and generates more accurate amplification products when amplifying regions with high GC content.

Hot-start variants of Taq DNA polymerase

Since Taq polymerase needs to be activated at higher temperatures, non-specific products may be produced at the beginning of the PCR reaction. To overcome this problem, hot-start PCR enzymes have been introduced, including an inactive variant at low temperatures and activatable at high temperatures. This helps to reduce the formation of non-specific products in the early stages of the PCR reaction, thereby improving specificity.

Since Taq polymerase needs to be activated at higher temperatures, non-specific products may be generated at the beginning of the PCR reaction. To overcome this problem, hot-start PCR enzymes have been introduced, including an inactive variant at low temperatures and activatable at high temperatures. This helps to reduce the formation of non-specific products in the early stages of the PCR reaction, thereby improving specificity.