Deoxyribonuclease

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deoxyribonuclease I
Identifiers
Symbol(s)	DNASE1 DNL1
Entrez	1773
OMIM	125505
RefSeq	NM_005223
UniProt	P24855
Other data
EC number	3.1.21.1
Locus	Chr. 16 p13.3

deoxyribonuclease II alpha
Identifiers
Symbol(s)	DNASE2 DNASE2A, DRN2, DNL, DNL2
Entrez	1777
OMIM	126350
RefSeq	NM_001375
UniProt	O00115
Other data
EC number	3.1.22.1
Locus	Chr. 19 p13.2

deoxyribonuclease II beta
Identifiers
Symbol(s)	DNASE2B
Entrez	58511
OMIM	608057
RefSeq	NM_021233
UniProt	Q8WZ79
Other data
EC number	3.1.22.1
Locus	Chr. 1 p22.3

A deoxyribonuclease (DNase, for short) is any enzyme that catalyzes the hydrolytic cleavage of phosphodiester linkages in the DNA backbone. Deoxyribonucleases are thus one type of nuclease. A wide variety of deoxyribonucleases are known, which differ in their substrate specificities, chemical mechanisms, and biological functions.

[edit] Modes of action

Some DNases cleave only residues at the ends of DNA molecules (exodeoxyribonucleases, a type of exonuclease). Others cleave anywhere along the chain (endodeoxyribonucleases, a subset of endonucleases). Some are fairly indiscriminate about the DNA sequence at which they cut, while others, including restriction enzymes, are very sequence-specific. Some cleave only double-stranded DNA, others are specific for single-stranded molecules, and still others are active toward both.

[edit] Types of deoxyribonucleases

The two main types of DNase found in metazoans are known as deoxyribonuclease I and deoxyribonuclease II.

Deoxyribonuclease I 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. DNase I is also a polymerization initiator for the cytoskeletal protein actin. It has been suggested to be one of the deoxyribonucleases responsible for DNA fragmentation during apoptosis.

Deoxyribonuclease II, or Acid DNase, hydrolyzes deoxyribonucleotide linkages in native and denatured DNA yielding products with 3'-phosphates. As the name implies, it is more effective at acid pHs. There are several known DNases II, including DNase II alpha (usually just called DNase II) and DNase II beta (also called DLAD, or DNase II-Like Acid DNase).

Other types of DNase include Microccocal nuclease.