Deoxyribonuclease I, referred to as DNase I, derived from recombinant E. coli strains, is an endonuclease that can digest single-stranded or double-stranded DNA, does not contain RNase, and can be used for various RNA samples of purification. DNase I hydrolyzes phosphodiester bonds to produce mono- and oligodeoxynucleotides containing 5'-phosphate and 3'-OH groups. The optimum working pH range is 7~8. The activity of DNase I depends on Ca 2+ and can be activated by divalent metal ions such as Co 2+ , Mn 2+ , Zn 2+ , etc. In the presence of Mg 2+ , DNase I can randomly cut double-stranded DNA at any position; in the presence of Mn 2+, DNase I can cut DNA double-strands at the same position, forming blunt ends or 1~2 sticky ends with nucleotide overhangs.