Taq and Pfu Polymerase

Difference Between Taq and Pfu Polymerase

Introduction of Taq and Pfu Polymerase

Taq and Pfu Polymerase differ significantly by possessing either 5′-3′ exonuclease proofreading activity or 3′-5′ exonuclease proofreading activity, respectively.

DNA polymerase catalyzes the production of new DNA during replication by using template DNA strands as precursors to synthesize complementary strands, acting like an exonuclease and helping with proofreading and damage repair via its exonuclease activity.

Taq and Pfu polymerase enzymes belong to either family A or family B. Both play an essential role in polymerase chain reactions (PCR).

What is Taq polymerase?

Taq polymerase is an indispensable enzyme in molecular biology, specifically developed for use in polymerase chain reaction (PCR). Produced by Thermus aquaticus extremophilic bacteria, Taq polymerase boasts remarkable heat resistance remaining active at elevated temperatures during cycles of denaturation, annealing, and extension processes in PCR.

Taq polymerase synthesizes complementary DNA strands by adding nucleotides onto DNA templates thus amplifying target sequences more easily. Taq polymerase stands out from other polymerases by its lack of 3′ to 5′ exonuclease activity or proofreading ability, or “proofreading ability”.

Taq polymerase
Figure 01: Taq polymerase

This makes Taq prone to producing errors or mutations when replicating DNA at elevated temperatures without degradation occurring. This property ensures Taq’s use for denaturation (separating the strands).

Applications extend beyond PCR such as genotyping and DNA sequencing as Taq can assist in detecting genetic variations and creating complementary DNA strands respectively.

Taq polymerase’s remarkable thermostability distinguishes it from proofreading polymerases, making it a reliable partner in molecular biology techniques like PCR. Although its error rate may be higher compared to proofreading polymerases, Taq is an efficient workhorse enzyme.

What is Pfu Polymerase?

Pfu Polymerase, also known as Pyrococcus furiosus DNA polymerase, is a widely used DNA replication enzyme in molecular biology and genetic research. Derived from an extremophilic archaeon known as Pyrococcus furiosus it thrives in extreme environments like hydrothermal vents and hot springs.

Pfu Polymerase is highly esteemed due to its precise DNA replication capabilities; making it a valuable asset in various laboratory techniques.

Pfu Polymerase’s primary hallmark is its 3′ to 5′ exonuclease proofreading activity, which allows it to correct errors during DNA synthesis, leading to a remarkably low error rate when copying DNA sequences. As such, Pfu Polymerase is often chosen in experiments where maintaining accuracy of sequence accuracy is of primary concern.

Pfu Polymerase
Figure 02: Pfu Polymerase

Pfu Polymerase is often utilized in high-fidelity PCR experiments where researchers need to amplify DNA with minimal risk of mutation or error introduction, or applications like sequencing and site-directed mutagenesis where precision is of vital importance.

Pfu Polymerase stands out among polymerases for its high fidelity; however, its heat sensitivity makes it less appealing than some alternatives such as Taq polymerase. Researchers must select Pfu Polymerase carefully in accordance with both the fidelity and temperature requirements of their experiments to ensure accurate DNA replication in molecular biology applications.

The Importance of Temperature Stability: Taq vs Pfu Polymerase

Temperature stability is an integral component of DNA polymerase enzymes like Taq and Pfu Polymerase for molecular biology techniques such as PCR.

Here is a comparison of their importance:

  • Taq Polymerase Is Renowned for Its Outstanding Thermostability: Taq Polymerase has become famous for its superb thermostability. This thermostability enables it to withstand high temperatures (around 94-98degC) necessary for DNA denaturation during PCR, providing stable operation despite cycles of denaturation, annealing, and extension that take place over many cycles.
  • Taq Polymerase remains active: Through these changes without succumbing to inactivity due to temperature fluctuations caused by temperature changes during these cycles allowing it to remain active over this entire process allowing PCR cycles while remaining active during all cycles without losing effectiveness over time.
  • Taq Polymerase’s ability: To work at high temperatures is essential to efficient DNA amplification. Taq Polymerase’s denaturation step – where DNA template strands separate – is key in this process and requires reliable execution by Taq Polymerase.
  • Convenience: Taq Polymerase’s thermostability greatly simplifies PCR protocols, as it eliminates the need to replenish enzymes during high-temperature cycles – further simplifying experiments.
  • Pfu Polymerase Exhibiting High Thermostability: Pfu Polymerase displays remarkable thermostability, being able to tolerate temperatures as high as 95-100degC without becoming unstable – this feature makes Pfu Polymerase particularly advantageous when extended exposure to extreme heat is required.
  • High Fidelity: Pfu Polymerase’s main advantage lies in its proofreading activity, but its thermostability ensures it can maintain high-fidelity PCR even under high-temperature conditions, making it the ideal solution when accuracy is key.
  • Precision Experiments: Pfu Polymerase’s temperature stability helps ensure accurate DNA replication during high-temperature denaturation and extension steps, such as site-directed mutagenesis and DNA sequencing experiments that require precision.

Taq Polymerase: Features and Applications.

Taq Polymerase is highly thermostable, meaning it can withstand temperatures (typically between 94-98degC) required for DNA denaturation in PCR without degrading over multiple cycles of DNA amplification. This allows it to remain active through multiple rounds without losing activity or becoming degraded over time.

  • DNA Polymerization: Taq Polymerase is responsible for creating new DNA strands during PCR by adding complementary nucleotides to an existing template during the extension stage of PCR.
  • Taq Polymerase Lack of Proofreading Activity: Taq Polymerase does not possess 3′ to 5′ exonuclease proofreading activity, meaning it does not correct errors that arise during DNA replication and thus has an unfavorably high error rate, making it more likely to introduce mutations during DNA amplification.
  • Taq Polymerase is an integral part of polymerase chain reaction (PCR): Used to amplify specific DNA sequences by repeatedly replicating them, PCR forms an essential foundation for molecular biology and genetic research.
  • Genotyping: Taq Polymerase can be used in genotyping assays to detect genetic variations and polymorphisms within DNA samples, making them useful in the identification of certain traits or markers.
  • DNA Sequencing: Although Taq Polymerase may not be as popular, its proofreading activity makes it useful in sequencing processes like Sanger sequencing to produce complementary strands of DNA strands.
  • Routine DNA Amplification: Taq Polymerase is frequently chosen for routine PCR experiments where high fidelity isn’t the priority, such as testing for specific DNA sequences or amplifying DNA for downstream applications.

Pfu Polymerase: Features and Applications.

Pfu Polymerase is known for its high level of accuracy when replicating DNA. Thanks to its 3′ to 5′ exonuclease proofreading activity, which corrects errors that arise during DNA synthesis, Pfu Polymerase boasts an extremely low error rate compared to other DNA polymerases such as Taq Polymerase.

  • Temperature Stability: Like Taq Polymerase, Pfu Polymerase is highly thermostable. It can withstand extremely high temperatures of 95-100degC without denatured, making it suitable for applications requiring high-temperature denaturation such as PCR.
  • Accuracy: Pfu Polymerase is ideal for experiments in which maintaining the integrity and accuracy of DNA sequence is of utmost importance, with its proofreading activity helping ensure minimal error or mutation insertions.
  • Applications: High-Fidelity PCR: Pfu Polymerase is most often employed for high-fidelity PCR applications. Researchers opt for this enzyme when they need to amplify DNA with extreme accuracy and minimal mutation risk; its most popular applications include cloning, site-directed mutagenesis, and DNA sequencing.
  • Site-Directed Mutagenesis: Pfu Polymerase provides an invaluable method of precisely inserting mutations into DNA sequences, making this method essential for studying the effects of specific genetic modifications.
  • DNA sequencing method: Pfu Polymerase can be utilized in DNA sequencing methods such as Sanger sequencing to generate error-free complementary DNA strands for accurate sequence determination.
  • Cloning: Researchers often utilize Pfu Polymerase in cloning experiments where maintaining the correct DNA sequence is of vital importance to subsequent applications.

Key Difference Between Taq and Pfu Polymerase

Taq polymerase has 5′-3′ exonuclease proofreading activity and Pfu polymerase is able to perform 3′-5′ exonuclease-based proofreading. So, this is the primary distinction between Taq Pfu and Pfu polymerase.

Taq polymerase was named after the bacteria Thermus Aquarius, and Pfu polymerase was named in honor of an archaeon Pyrococcus furiosus. Taq polymerase belongs to the DNA polymerase A group, while Pfu polymerase is part of that group, DNA Polymerase Group B.

Here’s a simplified comparison chart between Taq Polymerase and Pfu Polymerase:

Characteristic Taq Polymerase Pfu Polymerase
Source Thermus aquaticus bacterium Pyrococcus furiosus archaeon
Thermostability Highly thermostable, withstands 94-98°C Highly thermostable, tolerates 95-100°C
Fidelity Low fidelity, lacks proofreading High fidelity, with proofreading activity
Error Rate Higher error rate, prone to mutations Lower error rate, more accurate replication
DNA Denaturation Suitable for high-temperature denaturation Suitable for high-temperature denaturation
Exonuclease Activity Lacks 3′ to 5′ exonuclease proofreading Possesses 3′ to 5′ exonuclease proofreading
Applications Routine PCR, genotyping High-fidelity PCR, cloning, DNA sequencing
Suitable for Complex Templates Limited for complex templates Ideal for complex templates
Cost Cost-effective More expensive
Speed vs. Fidelity Faster but lower fidelity Slower but higher fidelity
Multiplex PCR Suitable, but accuracy may be compromised Preferred for accuracy in multiplex PCR
Overall Performance Reliable for routine applications Precise and accurate, especially for critical experiments

Considerations for Multiplex PCR: Taq vs Pfu Polymerase

Taq Polymerase:


  • High thermostability and Robust performance: Taq Polymerase offers numerous advantages for denaturation in multiplex PCR reactions at high temperatures, its thermostability ensures effective separation of DNA strands. Its robust performance is being used widely across laboratories to perform routine as well as multiplex amplification processes.
  • Cost-Effectiveness: Taq Polymerase tends to be more cost-efficient than enzymes with proofreading activity.


Lack of proofreading: Due to a lack of proofreading activity, Taq Polymerase tends to have a higher error rate, leading to misincorporation errors and multiplex amplification missteps that may compromise accuracy if high accuracy is crucial. Pfu Polymerase provides another solution.

Pfu Polymerase:

  • High fidelity: Pfu Polymerase provides higher fidelity than most alternative polymerases due to its proofreading activity, providing greater accuracy for multiplex PCR when precise sequence information is required.
  • Reduced error rate: Pfu Polymerase’s lower error rate helps preserve the integrity of amplified sequences during complex multiplex reactions, helping maintain their integrity while amplifying sequences at an increased rate.


  • Slower extension rate: Pfu Polymerase tends to have a slower extension rate compared to Taq Polymerase, potentially leading to longer reaction times during multiplex PCR experiments something to keep in mind as well.
  • Template Complexity: Pfu Polymerase’s higher fidelity may prove advantageous for templates containing challenging regions (e.g., high GC content, secondary structures or repetitive sequences), to maintain the integrity of amplified products.
  • Accuracy vs. Speed: When selecting between Taq and Pfu for multiplex PCR experiments, take into consideration both accuracy and speed considerations when making your selection. Pfu provides greater precision but may take more time for complete.
  • Error Tolerance: Take into account your acceptable tolerance for error when designing a multiplex assay. Taq Polymerase may suffice when minor discrepancies in final results are accepted while Pfu Polymerase should be chosen for applications requiring high accuracy.
  • Budget and Resources: Review both your budget and resources when considering Pfu Polymerase over Taq as it typically costs more. Consider whether its increased cost is justified by increased fidelity.
  • Optimization: No matter which polymerase is chosen, optimizing primer design, reaction conditions and cycling parameters is of utmost importance for successful multiplex PCR.

Choosing the Right Polymerase for Your PCR Experiment

 Polymerase Type:

  • Taq Polymerase: For general, routine PCR applications where the speed of DNA amplification is the main concern, Taq Polymerase can provide excellent value and thermostability with its cost-effective price point and quick activation time.
  • High-Fidelity Polymerases (e.g. Pfu or Phusion): When accurate DNA replication is required, selecting a high-fidelity polymerase with proofreading activity and lower error rates during DNA amplification is ideal for cloning, sequencing, and precision experiments.

Template Complexity:

  • High GC Content or Complex Templates: For templates containing high GC contents or complex sequences with secondary structures or challenging sequences, consider using a high-fidelity polymerase such as Pfu to maintain accuracy and ensure precision.

 Error Tolerance:

  •  Low Error Tolerance: If your experiment requires minimal introduction of errors or mutations, choose a high-fidelity polymerase to ensure accurate DNA amplification.

Balance Between Speed and Fidelity:

  • Speed: Taq Polymerase tends to be faster in DNA amplification compared to high-fidelity polymerases, so be mindful of striking an appropriate balance between speed and fidelity based on your experimental goals.
  • Multiplex PCR: When conducting multiplex PCR with multiple target sequences, select a polymerase that best meets the complexity of your template and accuracy requirements. High-fidelity polymerase solutions often make the best choice.
  • Hot-Start PCR: Hot-start polymerase variants can help minimize nonspecific amplification at lower temperatures, providing greater specificity than with traditional variants of your chosen polymerase. Consider selecting one if enhanced specificity is a priority for you.


  • Clash with Budget Restrictions: Taq Polymerase can often be more cost-effective than high-fidelity polymerases; if cost is a key consideration and high fidelity isn’t essential, Taq may be an appropriate solution.

Optimization Clash With Optimization Strategies:

  • Primer Design: No matter which polymerase is selected, takes time and effort to design optimal primers to ensure targeted and efficient amplification.
  • Reaction Conditions: For optimal results with any polymerase enzyme, ensure optimal reaction conditions such as annealing temperature and Mg2+ concentration are met.

Which Polymerase Should You Choose?

Amplifying challenging templates, such as those containing high GC content, secondary structures or complex sequences requires selecting an appropriate DNA polymerase enzyme – Taq or Pfu depending on what challenges the template presents.

Taq Polymerase boasts several advantages for DNA denaturation:

  • High thermostability and robust performance: These features make it particularly well suited to templates with high GC content and challenging sequences. In terms of reliability, Taq Polymerase has long been relied on as the go-to PCR enzyme.


  • Lack of Proofreading Activity: Taq Polymerase does not incorporate exonuclease proofreading, leading to an increased error rate and possibly leading to amplifying complex templates with errors introduced through amplification.

Pfu Polymerase offers additional proofreading features:


  • High fidelity: Pfu Polymerase excels at maintaining DNA replication accuracy due to its proofreading activity, making it a suitable option for complex sequences or regions prone to errors.


  • Slightly lower speed: Pfu Polymerase may have a slightly lower extension rate compared to Taq Polymerase, which could impact how quickly PCR runs.

Which Polymerase Should You Select for Amplifying Templates with High GC Content:

  • High GC Content: Its mes When amplifying templates with high GC content, Taq Polymerase’s robust thermostability may prove helpful in amplifying DNA fragments efficiently. However, for precise sequence accuracy, Pfu Polymerase may offer greater proofreading capacity which might make the more suitable choice.
  • Complex Sequences: Pfu Polymerase’s high fidelity and proofreading activity make it more suitable than many other polymerases for templates with complex or error-prone sequences, including those featuring repeated motifs, secondary structures or known mutations.
  • Speed versus Fidelity: Strike the appropriate balance between speed and accuracy when selecting Taq Polymerase or Pfu Polymerase as they both vary in terms of their speed/accuracy ratios; Taq is generally faster, yet less accurate, while Pfu is slower but more precise consider which tradeoff best meets your experimental goals when making this decision.
  • Cost and Convenience: Taq Polymerase tends to be more cost-effective and practical for general applications, whereas Pfu Polymerase may require more time and cost due to its proofreading properties.


Taq Polymerase and Pfu Polymerase are two DNA polymerase enzymes widely used in molecular biology. Taq Polymerase comes from Thermus aquaticus bacteria, and is highly thermostable but has low fidelity due to a lack of proofreading activity making it suitable for routine PCR and genotyping applications.

Error rates associated with Pfu Polymerase from Pyrococcus furiosus archaeon, however, make it less suitable for precise experiments due to its higher error rate. Meanwhile, its thermostability offers high fidelity when coupled with 3′-5′ exonuclease proofreading for accuracy in 3′ to 5′ exonuclease proofreading experiments.

Preferred for use in high-fidelity PCR, cloning, and precision experiments where maintaining accurate DNA replication is paramount. Taq Polymerase is known for its robustness and cost-efficiency.

Pfu Polymerase excels at applications requiring precision with minimal error introduction. Researchers select between them according to their experiment’s requirements.