DNase

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.
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.DNase enzymes can be inhaled using a nebuliser by cystic fibrosis sufferers. DNase enzymes help because white blood cells accumulate in the mucus and when they breakdown they release DNA which adds to the 'stickiness' of the mucus. DNase enzymes breakdown the DNA and the mucus is much easier to clear from the lungs.
Types of deoxyribonucleases


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