FAQ: What are the differences between the numerous Q5® Polymerase products available?

Stand-Alone Enzyme formulations (NEB #M0491, #M0493) are recommended for flexible PCR setup and for high GC content templates (by adding the High GC Enhancer to the reaction).
Master Mix formulations (NEB #M0492, #M0494) offer the most convenience by containing enzyme, Mg2+, dNTPs, and all necessary buffer components to support robust amplification - only template and primers need to be added.

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Hot Start formulations (NEB #M0493, #M0494) inhibit the activity of the enzyme, allowing for convenient room temperature reaction set up, and are suitable for all PCR applications requiring greater accuracy, high specificity or the amplification of difficult or long targets. For more information on Hot Start technology, click here.
NEBNext® Q5 formulations (NEB #M0541, #M0543, #M0544) have been specifically optimized to limit GC bias during the amplification of NGS libraries. M0544 is the suggested master mix for NGS applications.

The Q5 Blood Direct 2X Master Mix (NEB #M0500) is specially formulated for blood samples without the need for a purification step. It is a Hot Start enzyme.

Q5 polymerase cannot read through or incorporate uracil, but Q5U® Hot Start High-Fidelity DNA Polymerase (NEB #M0515) can. Use it with uracil-containing, bisulfite-converted, deaminated, or damaged DNA templates. Carryover contamination prevention can be utilized with Q5U and dUTP/dTTP. It is a Hot Start enzyme.