DNase I is a divalent cation-requiring endodeoxyribonuclease that can be used to
degrade single-or double-stranded DNA. The principle is that DNase I hydrolyzes
phosphodiester bonds to generate mononucleotides or oligonucleotides with
5'-phosphate groups and 3'-OH. Either Mg2+ or Mn2+ can activate the activity of DNase
I, while the concentration of Ca2+ directly affects the activity of the enzyme. In the
presence of Mg2+, nicks can be randomly generated on each single strand
ofdouble-stranded DNA; while in the presence of Mn2+ double-stranded DNA can be
broken.