T7 Endonuclease I (T7EI) is a special DNA Endonuclease, derived from the recombinant T7 Endonuclease I gene expressed by E.coli. It can cleave the non-perfectly matched DNA, cruciform DNA structures, Holliday structured or junctions DNA, and heteroduplex DNA, as well as cleave nicked double-stranded DNA to a lesser extent. Note that the length of insertion, deletion or mutation fragment for T7EI recognition must be ≥ 2 bp, and the cleavage site is the first, second or third phosphodiester bond at the 5 'end of the mismatch base. This product is commonly used for the detection of mutants formed by CRISPR/Cas9, TALEN or other gene editing tools, the detection of gene point mutation and SNP, and the random cleavage of linear DNA for shotgun cloning.