Deoxyribonuclease I (DNase I) is an endonuclease which is secreted to cleave DNA in the extracellular space down to an average of tetranucleotides with 5′ monophosphate and 3′ hydroxyl DNA ends . Both single-stranded DNA and double-stranded DNA are degraded by Dnase I. This nuclease appears to account for the major nucleolytic activity on DNA in serum and is responsible for the degradation of the majority of circulating DNA derived from apoptotic and necrotic cell death and from neutrophil extracellular traps. In addition to its role in the serum, it has been proposed as one of the deoxyribonucleases responsible for DNA fragmentation in the process of apoptosis.
