Deoxyribonuclease I digests single- and double-stranded DNA into a mixture of mono- and oligonucleotides with 5′ phosphate and 3′ hydroxyl termini. This catalytic activity is dependent on divalent ions. In the presence of Mg2+, deoxyribonuclease I randomly and independently hydrolyzes each strand of double-stranded DNA. In the presence of Mn2+, both strands can be cleaved.
Used in molecular biology applications for DNA removal during RNA purification, for preparing DNA for nick translation, and for analyzing DNA-protein interactions by footprinting. RNAase-free deoxyribonuclease I solutions from bovine pancreas have been used to digest DNA in a variety of samples.