Deoxyribonuclease I (usually called
DNase I), is an
endonuclease coded by the human gene
DNASE1. DNase I is a
nuclease that cleaves
DNA preferentially at phosphodiester linkages adjacent to a
pyrimidine nucleotide, yielding 5'-phosphate-terminated polynucleotides with a free hydroxyl group on position 3', on average producing tetranucleotides. It acts on single-stranded DNA, double-stranded DNA, and
chromatin. In addition to its role as a waste-management
endonuclease, it has been suggested to be one of the
deoxyribonucleases responsible for DNA fragmentation during
apoptosis.