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  • Exonuclease I (E. coli)

    recombinant unique buffer incubation temp heat inactivation
    Catalog #SizeConcentrationPriceQtyAdd to Cart
    M0293S3,000 units20,000 units/ml$65.00Add to Cart
    M0293L15,000 units20,000 units/ml$260.00Add to Cart
    Nuclease Products


    Catalyzes the removal of nucleotides from single-stranded DNA in the 3' to 5' direction.


    • Isolated from a recombinant source
    • 3' → 5' single strand exonuclease
    • Supplied with 10X Reaction Buffer

    Product Source

    An E. coli strain that carries the cloned Exo I gene from E. coli NM554.

    Reagents Supplied

    The following reagents are supplied with this product:

    Store at (°C)Concentration
    Exonuclease I Reaction Buffer-2010X

    Advantages and Features


    • Exonuclease I degrades excess single-stranded primer oligonucleotide from a reaction mixture containing double-stranded extension products

    Properties and Usage

    Unit Definition

    One unit is defined as the amount of enzyme that will catalyze the release of 10 nmol of acid-soluble nucleotide in a total reaction volume of 50 μl in 30 minutes at 37°C in 1X Exonuclease I Reaction Buffer with 0.17 mg/ml single-stranded [3H]-DNA.

    Reaction Conditions

    1X Exonuclease I Reaction Buffer
    Incubate at 37°C

    1X Exonuclease I Reaction Buffer:
    67 mM Glycine-KOH
    6.7 mM MgCl2
    10 mM β-ME
    pH 9.5 @ 25°C

    Usage Concentration

    10,000 units/ml

    Storage Temperature


    Storage Conditions

    10 mM Tris-HCl
    100 mM NaCl
    5 mM β-ME
    0.5 mM EDTA
    100 μg/ml BSA
    50% Glycerol
    pH 7.5 @ 25°C

    Heat Inactivation

    80°C for 20 min

    Quality Control

    Quality Control Assays

    The following Quality Control Tests are performed on each new lot and meet the specifications designated for the product. Individual lot data can be found on the Product Summary Sheet/Datacard or Manual which can be found in the Supporting Documents section of this page.
    • Endonuclease Activity (Nicking):
      The product is tested in a reaction containing a supercoiled DNA substrate. After incubation for 4 hours the percent converted to the nicked form is determined by agarose gel electrophoresis.
    • Exonuclease Activity (Radioactivity Release):
      The product is tested in a reaction containing a radiolabeled mixture of single and double-stranded DNA. After incubation for 4 hours the exonuclease activity is determined by the % release of radioactive nucleotides.
    • Protein Purity (SDS-PAGE):
      The physical purity is assessed by comparing contaminating protein bands in a concentrated sample to the protein of interest band in a sample of known dilution. The purity is determined by SDS-PAGE.


    1. Lehman and Nussbaum (1964). J. Biol. Chem. 239
    2. Kusher, et al. (1971). Proc. Natl. Acad. Sci. USA. 68
    3. Kusher et al. (1972). Proc. Natl. Acad. Sci. USA. 69, 1366.
    4. Goldmark and Linn (1972). J. Biol. Chem. 247
    5. Rosamond et al. (1979). J. Biol. Chem. 254

    Supporting Documents

    Material Safety Datasheets

    The following is a list of Material Safety Data Sheets (MSDS) that apply to this product to help you use it safely. The following file naming structure is used to name these document files: [Product Name] MSDS. For international versions please contact us at info@neb.com.


    The Product Summary Sheet, or Data Card, 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 the majority of these document files: [Catalog Number]Datasheet-Lot[Lot Number]. For those product lots not listed below, please contact NEB at info@neb.com or fill out the Technical Support Form for appropriate document.
    1. Can Exonuclease I be used to remove primers from amplification reactions?
    2. Will Exonuclease I degrade RNA?
    3. Can Exonuclease I be used to blunt DNA?
    4. Can Exonuclease I be heat inactivated?
    5. Can Exonuclease I be used with a double stranded exonuclease to clean up plasmid preparations?
    6. Will Exonuclease I work in other buffers?

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