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  • Q5® Site-Directed Mutagenesis Kit (Without Competent Cells)


    The Q5 Site-Directed Mutagenesis Kit (Without Competent Cells) enables rapid, site-specific mutagenesis of double-stranded plasmid DNA in less than 2 hours (Figure 1). The kit utilizes the robust Q5 Hot Start High-Fidelity DNA Polymerase along with custom mutagenic primers to create insertions, deletions and substitutions in a wide variety of plasmids. After PCR, the amplified material is added directly to a unique Kinase-Ligase-DpnI (KLD) enzyme mix for rapid (5 minutes), room temperature circularization and template removal (Figure 2). Transformation into high-efficiency chemically-competent E. coli, not supplied, ensures robust results with plasmids up to at least 20 kb in length.

    Figure 1: Site-specific mutagenesis proceeds in less than 2 hours.Figure 1: Site-specific mutagenesis proceeds in less than 2 hours.

    The use of a master mix, a unique multi-enzyme KLD enzyme mix, and a fast polymerase ensures that, for most plasmids, the mutagenesis reaction is complete in less than two hours.
    Figure 2: Q5 Site-Directed Mutagenesis Overview.Figure 2: Q5 Site-Directed Mutagenesis Overview.

    This kit is designed for rapid and efficient incorporation of insertions, deletions and substitutions into doublestranded plasmid DNA. The first step is an exponential amplification using standard primers and a master mix fomulation of Q5 Hot Start High-Fidelity DNA Polymerase. The second step involves incubation with a unique enzyme mix containing a kinase, a ligase and DpnI. Together, these enzymes allow for rapid circularization of the PCR product and removal of the template DNA. The last step is a high-efficiency transformation into chemicallycompetent cells (not provided).
    Figure 3: Primer Design for Q5 Site-Directed MutagenesisFigure 3: Primer Design for Q5 Site-Directed Mutagenesis

    Substitutions, deletions and insertions are incorporated into plasmid DNA through the use of specifically designed forward (black) and reverse (red) primers. Unlike kits that rely on linear amplification, primers designed for the Q5 Site-Directed Mutagenesis Kit should not overlap to ensure that the benefits of exponential amplification are realized. A) Substitutions are created by incorporating the desired nucleotide change(s) (denoted by *) in the center of the forward primer, including at least 10 complementary nucleotides on the 3´side of the mutation(s). The reverse primer is designed so that the 5´ends of the two primers anneal backto-back. B) Deletions are engineered by designing standard, non-mutagenic forward and reverse primers that flank the region to be deleted. C) Insertions less than or equal to 6 nucleotides are incorporated into the 5´ end of the forward primer while the reverse primer anneals back-to-back with the 5´ end of the complementary region of the forward primer. D) Larger insertions can be created by incorporating half of the desired insertion into the 5´ ends of both primers. The maximum size of the insertion is largely dictated by oligonucleotide synthesis limitations.

    Kit Components

    The following reagents are supplied with this product:

    Store at (°C)Concentration
    Q5® Hot Start High-Fidelity 2X Master Mix-202X
    KLD Enzyme Mix-2010X
    KLD Reaction Buffer-202X
    Control SDM Primer Mix-2010 μM
    Control SDM Plasmid-205 μg/ml

    Advantages and Features


    • Non-overlapping primer design ensures robust, exponential amplification, generating a high percentage of desired mutations from a wide range of templates
    • Intramolecular ligation and transformation into NEB high-efficiency competent cells results in high colony yield
    • Extremely low error rate of Q5 Hot Start High-Fidelity DNA Polymerase reduces screening time
    • Hot start polymerase enables room temperature reaction set-up
    • DpnI background reduction permits a wide range of starting template concentrations
    • Use of standard primers eliminates additional expenses from phosphorylated or purified oligos
    • Easy-to-use PCR master mix and unique multi-enzyme KLD mix offer convenience and quality
    • Rapid and direct treatment step proceeds at room temperature in 5 minutes
    • Allows the use of any chemically-competent E. coli cells suitable for cloning

    Properties and Usage

    Materials Required but not Supplied

    • Chemically-competent E. coli cells
    • SOC Outgrowth Media
    • Selection Plates

    Storage Temperature




    No/Low Colonies

    • Be sure to use high-efficiency chemically-competent E. coli cells. The following competent E. coli cells have been shown to work with this kit:
      NEB #C2987, NEB 5-alpha (High Efficiency) (standard recommendation)
      NEB #C2992, NEB 5-alpha F´Iq (High Efficiency)
      NEB #C3019, NEB 10-beta (High Efficiency)
      NEB #C2984, NEB Turbo
      NEB #C2566, T7 Express
      NEB #C3029, Shuffle® T7

      For convenience, we offer a version of the Q5 Site Directed Mutagenesis Kit prepackaged with
      NEB #C2987 NEB 5-alpha Competent E. coli (High Efficiency) cells in product number NEB #E0554.

      Other chemically competent E. coli strains suitable for cloning can be substituted. Results will vary according to the quality and efficiency of the cells.

    • Check that the transformation efficiency of the competent cells is ~1 x 109 colony forming units (cfu) per μg. To calculate transformation efficiency, transform 2 μl of pUC19 DNA (NEB #N3041) (100 pg) into 50 μl of cells. Follow the transformation protocol on page 8. Prior to plating, dilute 10 μl of cells up to 1 ml in SOC. Plate 100 μl of this dilution. In this case, 150 colonies will yield a transformation efficiency of 1.5 x 109 cfu/μg (μg DNA=0.0001, dilution=10/1000 x 100/1000).

    • Ensure that your primers are designed properly. To take advantage of the exponential nature of the amplification reaction, the 5´ ends of the two primers should align back-to-back unless deletions are being made (see Figure 3). For best results, primers should be designed and annealing temperatures calculated using NEBaseChanger, the NEB online primer design software.

    • Ensure there is a clean PCR product by visualizing 2–5 μl of the reaction on an agarose gel. Follow the suggestions below for low or impure PCR products.

    • Only use 1 μl of PCR product in the KLD reaction. Carrying too much PCR product forward can decrease transformation efficiency. If the PCR yield is low, more product can be added to the KLD reaction, however a buffer exchange step, such as PCR purification, must be included prior to transformation.

    • Only use 5 μl of the KLD reaction in the transformation. If more KLD reaction is added, a buffer exchange step, such as PCR purification, should be included prior to transformation.

    • Ensure that the selectable marker in the plasmid matches the selection agent used in the plates

    • Ensure the E. coli cells have been stored at –80°C.
    No/Low PCR Product

    • Ensure that the optimal annealing temperature (Ta) is used. High-Fidelity polymerases benefit from a Tm+3 annealing temp. Use NEBaseChanger, the NEB online primer design software, to calculate Ta. Alternatively, the optimal annealing temperature could be determined using a gradient PCR followed by agarose gel analysis.

    • Ensure that the elongation time is adequate for the plasmid length. We recommend 10–20 seconds per kb of plasmid.

    • Ensure that the final concentration of each primer is 0.5 μm.

    • Purify the primers with polyacrylamide gel electrophoresis (PAGE).
    Resulting Plasmids Do Not Contain the Desired Mutation

    • Ensure proper design of the mutagenic primers

    • Optimize the PCR conditions (see above)

    • Use 1–25 ng of template in the PCR step. A small increase in the number of clones with no/incorrect mutation incorporated can occur if less than 1 ng or more than 25 ng of template is used.


    1. Storage Note:
      The Q5 Site-Directed Mutagenesis Kit (Without Competent Cells) is stable at –20°C for two years. For flexibility, the mutagenesis reagents and control reactions are supplied without competent cells so that any chemically-competent E. coli cells suitable for cloning may be used.


    1. Kalnins et al. (1983). The EMBO Journal. 2, 593-597.


    1. How do I design primers to use with the Q5® Site-Directed Mutagenesis Kit?
    2. What should I use for an annealing temperature with the Q5® Site-Directed Mutagenesis Kit?
    3. Do I need to purify my plasmid before or after the KLD reaction when using the Q5® Site-Directed Mutagenesis Kit?
    4. What plasmid sizes can be amplified using the Q5® Site-Directed Mutagenesis Kit?
    5. What is the maximum number of nucleotides that can be inserted with this kit?
    6. What is the maximum distance that can be tolerated between substitutions?
    7. Typically, what percentage of transformants will have the desired mutation incorporated?
    8. What is the KLD Mix?
    9. What types of competent cells are compatible with this kit?
    10. If I double my PCR size, should I add more PCR mix to the KLD reaction?
    11. Why is the desired mutation missing from the transformants that I screened?
    12. Why do I not see my PCR product after using the Q5® Site-Directed Mutagenesis Kit?


    1. Q5® Site-Directed Mutagenesis Kit (Without Competent Cells) Quick Protocol (E0552)
    2. Q5® Site-Directed Mutagenesis Kit (Without Competent Cells) Protocol (E0552)
    3. Protocol for Control Reaction (E0552)


    The Product Manual includes details for how to use the product, as well as details of its formulation and quality controls. The following file naming structure is used to name these document files: manual[Catalog Number].

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    Safety Data Sheet

    The following is a list of Safety Data Sheet (SDS) that apply to this product to help you use it safely.