DNase I

DNase I (Deoxyribonuclease I) is an endodeoxyribonuclease that can digest single- or double- stranded DNA. It recognizes and cleaves phosphodiester bonds to produce monodeoxynucleotides or single- or double- stranded oligodeoxynucleotides with phosphate groups at the 5'-terminal and hydroxyl at the 3'-terminal. The activity of DNase I depends on Ca 2+ and can be activated by divalent metal ions such as Mn 2+ and Zn 2+ . 5 mM Ca 2+ protects the enzyme from hydrolysis. In the presence of Mg 2+ , the enzyme could randomly recognize and cleave any site on any strand of DNA. In the presence of Mn 2+ , the double strands of DNA can be simultaneously recognized and cleaved at almost the same site to form flat end DNA fragments or sticky end DNA fragments with 1-2 nucleotides protruding.