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  • Factor Xa Protease


    Factor Xa cleaves after the arginine residue in its preferred cleavage site Ile-(Glu or Asp)-Gly-Arg. It will sometimes cleave at other basic residues, depending on the conformation of the protein substrate (1,2,3). The most common secondary site, among those that have been sequenced, is Gly-Arg. There seems to be a correlation between proteins that are unstable in E.coli and those that are cleaved by Factor Xa at secondary sites; this may indicate that these proteins are in a partially unfolded state (Walker, I., Riggs, P., unpublished observations). Factor Xa will not cleave a site followed by proline or arginine.

    Product Source

    Factor Xa Protease is purified from bovine plasma and activated by treatment with the activating enzyme from Russell's viper venom.

    Properties and Usage

    Unit Definition

    1 μg of Factor Xa will cleave 50 μg of MBP fusion protein test substrate, MBP-ΔSal to 95% completion in a total reaction volume of 50 μl in 6 hours or less at 23°C in 20 mM Tris-HCl (pH 8.0 @ 25°C) with 100 mM NaCl and 2 mM CaCl2.

    Usage Concentration

    1 mg/ml

    Storage Temperature


    Molecular Weight

    Theoretical: 43 kDa


    Dansyl-glu-gly-arg-chloromethyl ketone (CALBIOCHEM, #251700) will irreversibly inactivate Factor Xa by covalent attachment at the active site. In a reaction containing 20 μg/ml Factor Xa, 2 μM dansyl-glu-gly-arg-chloromethyl ketone will inactivate >95% of the Factor Xa in 1 minute at room temperature.


    1. The test substrate MBP-ΔSal is maltose-binding protein fused to a truncated form of paramyosin, with the amino acids Ile-Glu-Gly-Arg at the fusion joint. Greater than 95% of the fusion protein is cleaved in 6 hours or less.


    1. Nagai, K. et al. (1985).
      1. Proc. Natl. Acad. Sci. USA
      . 82
    2. Quinlan, R.A. et al (1989).
      1. . Cell Sci
      . 82, 7252-7255.
    3. Eaton, D. et al (1986).
      1. Biochemistry
      . 25, 505-512.

    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.

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