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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/10/15 16:45:05」(JST)

A deoxyribonuclease (DNase, for short) is any enzyme that catalyzes the hydrolytic cleavage of phosphodiester linkages in the DNA backbone. Thus, deoxyribonucleases are 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[edit]

Some DNases cut, or "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 break down, they release DNA, which adds to the 'stickiness' of the mucus. DNase enzymes break down the DNA, and the mucus is much easier to clear from the lungs.

Types of deoxyribonucleases[edit]

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

Other types of DNase include Micrococcal nuclease.

Assay of deoxyribonucleases[edit]

DNA absorbs UV light with a wavelength of maximal absorbance near 260 nm. This absorption is due to the pi electrons in the aromatic bases of the DNA. In dsDNA, or even regions of RNA where double-stranded structure occurs, the bases are stacked parallel to each other, and the overlap of the base molecular orbitals leads to a decrease in absorbance of UV light. This phenomenon is called the hypochromic effect. When DNAse liberates nucleotides from dsDNA, the bases are no longer stacked as they are in dsDNA, so that orbital overlap is minimized and UV absorbance increases. This increase in absorbance underlies the basis of Kunitz unit of DNAse activity. One Kunitz unit is defined as the amount of enzyme added to 1 mg/ml salmon sperm DNA that causes an increase in absorbance of 0.001 per minute at the wavelength of 260 nm when acting upon highly polymerized DNA at 25 ºC in a 0.1 M NaOAc (pH 5.0) buffer. The unit's name recognizes the Russian-American biochemist M. Kunitz, who proposed the standard test in 1946.

A standard enzyme preparation should be run in parallel with an unknown because standardization of DNA preparations and their degree of polymerization in solution is not possible.

References[edit]

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English Journal

Detection of circoviruses and porcine adenoviruses in water samples collected from swine manure treatment systems.

Viancelli A, Garcia LA, Kunz A, Steinmetz R, Esteves PA, Barardi CR.SourceDepartamento de Microbiologia e Parasitologia, Laboratório de Virologia Aplicada, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, Santa Catarina, Brazil.
Research in veterinary science.Res Vet Sci.2012 Aug;93(1):538-43. Epub 2011 Aug 27.
Samples collected from two swine manure treatment systems including: swine manure treatment system and demonstrative unit (SMTS and DU), were analyzed by qPCR to quantify the amount of porcine adenovirus (PAdV) and porcine circovirus (PCV2) present. Positive samples were tested for virus integrity u
PMID 21872287

Transcriptomic studies of phosphate control of primary and secondary metabolism in Streptomyces coelicolor.

Martín JF, Santos-Beneit F, Rodríguez-García A, Sola-Landa A, Smith MC, Ellingsen TE, Nieselt K, Burroughs NJ, Wellington EM.SourceÁrea de Microbiología. Fac. CC. Biológicas y Ambientales, Universidad de León, Campus de Vegazana, s/n, 24071, Leon, Spain, degjmm@unileon.es.
Applied microbiology and biotechnology.Appl Microbiol Biotechnol.2012 Jul;95(1):61-75. Epub 2012 May 24.
Phosphate controls the biosynthesis of many classes of secondary metabolites that belong to different biosynthetic groups, indicating that phosphate control is a general mechanism governing secondary metabolism. We refer in this article to the molecular mechanisms of regulation, mediated by the two-
PMID 22622839

Japanese Journal

Regulatory genomic regions active in immune cell types explain a large proportion of the genetic risk of multiple sclerosis

Elangovan Ramyiadarsini I,Disanto Giulio,Berlanga-Taylor Antonio J [他]
Journal of human genetics 59(4), 211-215, 2014-04
NAID 40020043181

Enhanced Formation and Disordered Regulation of NETs in Myeloperoxidase-ANCA-Associated Microscopic Polyangiitis.

Nakazawa Daigo,Shida Haruki,Tomaru Utano,Yoshida Masaharu,Nishio Saori,Atsumi Tatsuya,Ishizu Akihiro
Journal of the American Society of Nephrology : JASN, 2014-01-02
… The activity of DNase I, an important regulator of NETs, was also lower in MPO-ANCA-associated MPA and SLE sera. … IgG depletion from MPO-ANCA-associated MPA sera partially restored the rate of NET degradation, and addition of DNase I synergistically enhanced this restoration. …
NAID 120005372312

好中球細胞外トラップの異常とMPO-ANCA 関連血管炎

石津明洋
日本小児腎臓病学会雑誌 27(2), 81-85, 2014
MPO-ANCA 関連血管炎（MPO-AAV）は，myeloperoxidase（MPO）を抗原とする抗好中球細胞質抗体（ANCA）の出現とともに，糸球体をはじめとする小型血管が侵される壊死性血管炎である。MPO-ANCA 自体の病原性が確認されているが，その産生機序は不明であった。我々は好中球細胞外トラップneutrophil extracellular traps（NETs）の異常がMPO-A …
NAID 130005067562

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★リンクテーブル★

リンク元	「DNA分解酵素」「DNA nuclease」「deoxyribonuclease」「DNAase」「デオキシリボヌクレアーゼ」
拡張検索	「DNase I」「ADNase B」