• Pfu DNA polymerase is a high-fidelity, thermostable DNA-dependent DNA polymerase originally isolated from the hyperthermophilic archaeon Pyrococcus furiosus (Lundberg et al., 1991). 
• Due to its exceptional thermostability and proofreading ability, Pfu polymerase has become a preferred enzyme for applications requiring accurate DNA amplification, such as cloning, mutagenesis, and sequencing.
• Pfu exhibits both 5′→3′ DNA polymerase activity and 3′→5′ exonuclease activity, the latter enabling it to remove incorrectly incorporated nucleotides during DNA synthesis. This proofreading function significantly reduces the error rate during polymerization, giving Pfu an error frequency of ~1 in 1.3 million base pairs, which is about 10 to 20 times more accurate than Taq polymerase.
• Its optimal activity occurs at 72°C, and it remains stable at the high denaturation temperatures used in PCR (typically 94–98°C). However, Pfu is generally slower than Taq, extending DNA at a rate of ~0.5–1 kb/min, and it produces blunt-ended PCR products, which can influence downstream cloning strategies.
• Pfu polymerase is ideal for applications requiring high fidelity, such as gene cloning, site-directed mutagenesis, and amplification for sequencing. Its precision and thermostability make it useful for amplifying templates with complex secondary structures or high GC content, though longer extension times are often necessary.
• In summary, Pfu DNA polymerase is a proofreading, high-accuracy enzyme suited for PCR applications where fidelity is critical. While it may be slower than other polymerases like Taq or Phusion, its ability to generate error-free DNA makes it indispensable in precision molecular biology workflows.

REFERENCES

• Lundberg et al., 1991. High-fidelity amplification using a thermostable DNA polymerase isolated from Pyrococcus furiosus.  Gene. 108(1), 1-6. PMID-1761218