T7 Endonuclease I, a stable homodimer of identical 149 amino acid subunits (1) is the product of a recombinant gene in E. coli . Double-stranded breaks (DSBs) generated by CRISPR/TALEN at desired target sites can be PCR-amplified, and the PCR products can be denatured and re-annealed to form mismatched DNA. If the mismatched DNA length position is more than 1 bp, T7 endonuclease I can recognize and cleave it. It is useful for quantitatively estimating the nuclease-induced mutation frequency of gene edited cells.


  • Resolve four-way junction or branched DNA
  • Detect or cleave heteroduplex and nicked DNA
  • Randomly cleave linear DNA for shot-gun cloning

Protein purity
The physical purity of this enzyme is ≥99% as assessed by SDS-PAGE with Coomassie® blue staining (see figure below).

T7 Endonuclease PurityProduct Source
E coli BL21 (DE3) pLysS strain expressing T7 Endonuclease I gene.

Product Includes

  • T7 Endonuclease I
  • 10x T7 Endonuclease I reaction buffer

1x T7 Endonuclease I reaction buffer
10 mM Tris-HCL, 50 mM KCl ,10 mM MgCl2  , 1 mM DTT, pH 7.5 @ 25ºC

Storage Buffer
50 mM Tris-HCl, 50 mM KCl, 1 mM DTT, 0.1 mM EDTA, 50% Glycerol, pH 7.5 @ 25ºC

Storage Temperature

 Quality Control assays
T7 Endonuclease I is free from detectable contaminating nuclease activities.