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Cat. No.
250 Units
500 Units
2500 Units

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Unique blend of highly-efficient MyTaq HS DNA Polymerase and a proprietary proofreading enzyme that combine to give increased target affinity for use with challenging templates and inhibitor-rich samples.

Product Highlights

  • Robust - enzyme blend and buffer system promotes reliable amplification of the most challenging and complex targets, even in the presence of inhibitors
  • Sensitive - improved target affinity and high processivity ensure successful amplification in low-copy number assays
  • Efficient - high-yield amplification of a broad range of targets up to 10 kb including complex DNA extracted from human, animal and plant samples
  • Specific - an antibody-mediated hot-start blend that remains completely inactive during PCR set-up to prevent non-specific amplification
  • Convenient - advanced buffer system minimizes the requirements for PCR optimization thereby reducing time to results and eliminating the cost of unnecessary repeats
  • Accurate - proofreading component delivers 3.5x higher fidelity than Taq DNA Polymerase, enabling cloning of PCR products

Product Description

MyFi™ has been developed to give reliable amplification of targets up to 10 kb from challenging and complex targets. MyFi shows improved tolerance to PCR inhibitors, thereby enabling reliable detection from samples from which DNA is difficult to purify. Furthermore a unique buffer system and enzyme blend promote highly sensitive amplification, ideal for low-copy number targets. The inclusion of MyTaq HS means MyFi generates PCR products with 3’-A overhangs making it suitable for TA cloning. MyFi has the added convenience of room temperature reaction assembly, to avoid non-specific amplification and primer-dimer formation.

An advanced buffer system and enzyme blend combine to give increased target affinity, ideal for amplification of cDNA libraries, complex genomic fragments and GC-rich targets.


  • Amplification of challenging and complex templates
  • Robust PCR
  • Longer PCR (up to 10 kb)
  • Low-copy PCR
  • TA cloning

PCR Enzyme Guide

Download the PCR Enzyme Guide with detailed product descriptions and performance data to help you choose the best product for your research

PCR Selection Chart

Select the best reagent for your research

We commonly use the Meridian MyFi polymerase, and it works better than any other polymerase. MyFi polymerase could amplify complicated short tandem repeat sequences (STR or SSR / microsatellite) better than any other kit.

Hiroshi Shinozuka, AgriBio, Bundoora, Australia

Product Selection

Please refer to the PCR Selection Chart to confirm the recommended product for your PCR application.




250 Units

500 Units

2500 Units

MyFi DNA Polymerase

1 x 125 µL

1 x 250 µL

2 x 625 µL

5x MyFi Reaction Buffer

1 x 625 µL

1 x 1.25 mL

5 x 1.25 mL


BIO-21117: 125 x 25 µL Reactions: 1 x 125 µL

BIO-21118: 250 x 25 µL Reactions: 1 x 250 µL

BIO-21119: 1250 x 25 µL Reactions: 2 x 625 µL


2 u/µL

Storage & Stability

All components should be stored at -20°C upon receipt for optimum stability. Repeated freeze/thaw cycles should be avoided.

When stored under the recommended conditions and handled correctly, full activity of the reagents is retained until the expiry date indicated on the outer box label.

Shipping conditions

On Dry Ice or Blue Ice.



"We commonly use the Meridian MyFi polymerase, and it works better than any ... "

"I like the Meridian MyFi polymerase, as it can amplify any sequence even if ... "

""For verification of difficult to detect genes this product worked ... "

""MyFi Taq allowed the same result with half of the sample and half of ... "

""MyFi gave best results with a long AT-rich template and two-step PCR ... "

""MyFi was able to produce high yield clean PCR product when Roche high ... "


At Meridian we pride ourselves in supplying high-quality polymerases to suit your requirements. To aid your selection of the most suited enzyme for your specific applications, please see our enzyme selection tool.

All our polymerases are guaranteed for a period of 12 months from the date of purchase. These should be stored at -20°C during this time for optimal retention of activity.

Please Note: We do not recommend the storage of our polymerases at -80 °C as ice crystals could form on the active site, which may affect or destroy the activity of the enzyme.

PCR can be a challenging technique, with various parameters to optimize to achieve the best results. If you are having problems, these could be easily resolved by addressing a few issues. Please see our PCR troubleshooting guide for suggestions and help with your specific problems.

Observation Recommended Solution(s)
No or low PCR yield  Enzyme concentration too low – increase the amount of enzyme in 0.5 U increments.
 Primers degraded – check quality and age of the primers.
 Magnesium concentration too low – increase concentration in 0.25 mM increments with a starting  concentration of 1.75 mM.
 Primer concentration not optimized. Titrate primer concentration (0.3-1 µM); ensuring that both  primers have the same concentration.
 Template concentration too low – Increase concentration of template.
 Perform a positive control to ensure that the enzyme, dNTPs and buffers are not degraded and/or contaminated.
Multiple Bands  Primer annealing temperature too low. Increase annealing temperature. Primer annealing should be at least 5°C below the calculated Tm of primers.
 Prepare master mixes on ice or use a heat-activated polymerase.
 For problems with low specificity. Try adding 3% DMSO (not supplied) to improve specificity.
Smearing or artifacts  Template concentration too high. Prepare serial dilutions of template.
 Too many cycles. Reduce the cycle number by 3-5 to remove non-specific bands.
 Enzyme concentration too high - decrease the amount of enzyme in 0.5 U increments.
 Extension time too long. Reduce extension time in 0.5-1 minute increments.

These terms refer to parameters to be considered when performing PCR and are important features in selecting the correct enzyme for your needs. Understanding what they mean is therefore crucial: Yield: The amount of DNA produced in a PCR reaction. Fidelity: The accuracy of the enzyme at incorporating the correct dNTP to the elongating DNA strand. Processivity: The length of time a polymerase is associated with the template and therefore the size of fragment which can be amplified. Specificity: A measure of the unwanted by-products generated in a reaction.

During PCR setup at room temperature, standard polymerases will have some activity. When using a hot-start polymerase, this enzyme will have no activity at room temperature, thus reducing the risk of unspecific products in the reaction due to these mis-primed oligonucleotides. This feature makes this type of polymerase ideally suited to high-throughput applications, where the reactions may be left sitting at room temperature for prolonged periods of time.

In nature, the ability of a DNA polymerase to correct misincorporations of nucleotides in the DNA strand being elongated is often crucial to the survival of the host organism. This ability is termed "proofreading activity" and occurs in the 3' to 5' direction. This activity also leads to the polymerase removing unpaired nucleotides overhanging at the 3'end (A-overhangs), creating blunt ends.

One unit is defined as the amount of enzyme that incorporates 10 nmoles of dNTPs into acid-insoluble form in 30 minutes at 72°C.

All Meridian polymerases are available in the convenient format of a 2x master mix, containing all the reagents and additives necessary to perform successful PCR, with the exception of template, primers and water. This formulation not only provides a convenient and hassle-free PCR setup, but also significantly reduces the chances of human error, inaccuracies and contamination by reducing the pipetting steps required.

If possible, we would recommend an additional cleanup of affected samples, for instance, customers had very good experiences with the clean-up of samples containing humic acids with SureClean Plus. Alternatively decreasing the template concentration will help to minimize the amount of inhibitors. The amount of primer can be increased, but do not exceed the suggested limits.

Please click here in order to request your sample. You will receive an email confirmation within two business days with delivery details.