Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/08/01 10:37:57」(JST)

wiki en

Crystals of DNase protein.

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 hyperchromic 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]

This hydrolase article is a stub. You can help Wikipedia by expanding it.

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. 嚢胞性線維症：肺疾患治療の概要 cystic fibrosis overview of the treatment of lung disease
2. 成人における肺炎随伴性胸水および膿胸 parapneumonic effusion and empyema in adults
3. Role of mucoactive agents and secretion clearance techniques in COPD
4. 小児における無気肺 atelectasis in children
5. 溶連菌感染後糸球体腎炎 poststreptococcal glomerulonephritis

English Journal

Enzymatic and hemolytic activity in different Candida species.

Riceto EB1, Menezes RP2, Penatti MP3, Pedroso RS4.Author information 1Curso de Ciências Biológicas, Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil; Curso Técnico em Análises Clínicas, Escola Técnica de Saúde, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil.2Programa de Pós-Graduação em Ciências da Saúde, Faculdade de Medicina, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil; Curso Técnico em Análises Clínicas, Escola Técnica de Saúde, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil.3Curso Técnico em Análises Clínicas, Escola Técnica de Saúde, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil.4Curso Técnico em Análises Clínicas, Escola Técnica de Saúde, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil. Electronic address: rpedroso@estes.ufu.br.AbstractBACKGROUND: Candida species, in conditions of microbiota imbalance or decreased immune defenses, may be one of the main human fungal pathogens. Virulence factors constitute the mechanisms used by the fungus to avoid host defenses.
Revista iberoamericana de micologia.Rev Iberoam Micol.2014 Apr 1. pii: S1130-1406(14)00019-9. doi: 10.1016/j.riam.2013.11.003. [Epub ahead of print]
BACKGROUND: Candida species, in conditions of microbiota imbalance or decreased immune defenses, may be one of the main human fungal pathogens. Virulence factors constitute the mechanisms used by the fungus to avoid host defenses.AIM: This study aimed to investigate the in vitro production of virule
PMID 24704439

Nucleases in higher plants and their possible involvement in DNA degradation during leaf senescence.

Sakamoto W1, Takami T.Author information 1Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan.AbstractDuring leaf senescence, macromolecules such as proteins and lipids are known to be degraded for redistribution into upper tissues. Similarly, nucleic acids appear to undergo fragmentation or degradation during senescence, but the physiological role of nucleic acid degradation, particularly of genomic DNA degradation, remains unclear. To date, more than a dozen of plant deoxyribonucleases have been reported, whereas it remains to be verified whether any of them degrade DNA during leaf senescence. This review summarizes current knowledge related to the plant nucleases that are induced developmentally or in a tissue-specific manner and are known to degrade DNA biochemically. Of these, several endonucleases (BFN1, CAN1, and CAN2) and an exonuclease (DPD1) in Arabidopsis seem to act in leaf senescence because they were shown to be inducible at the transcript level. This review specifically examines DPD1, which is dual-targeted to chloroplasts and mitochondria. Results show that, among the exonuclease family to which DPD1 belongs, DPD1 expression is extraordinary when estimated using a microarray database. DPD1 is the only example among the nucleases in which DNA degradation has been confirmed in vivo in pollen by mutant analysis. These data imply a significant role of organelle DNA degradation during leaf senescence and implicate DPD1 as a potential target for deciphering nucleotide salvage in plants.
Journal of experimental botany.J Exp Bot.2014 Mar 14. [Epub ahead of print]
During leaf senescence, macromolecules such as proteins and lipids are known to be degraded for redistribution into upper tissues. Similarly, nucleic acids appear to undergo fragmentation or degradation during senescence, but the physiological role of nucleic acid degradation, particularly of genomi
PMID 24634485

Polymerase proofreading-associated polyposis: a new, dominantly inherited syndrome of hereditary colorectal cancer predisposition.

Church JM.Author information Sanford R. Weiss, MD, Center for Hereditary Colorectal Neoplasia, Department of Colorectal Surgery, The Cleveland Clinic Foundation, Cleveland, Ohio.AbstractGermline mutations in the exonuclease (proofreading) domains of 2 DNA polymerases (POLE and POLD1) have been associated with a dominantly inherited, highly penetrant syndrome of oligo adenomatous polyposis and early-age-of-diagnosis colorectal cancer and endometrial cancer. The loss of proofreading capability causes multiple mutations throughout the genome and is manifest as microsatellite-stable, chromosomal unstable cancers. This is an important addition to the range of dominantly inherited syndromes of colorectal cancer predisposition.
Diseases of the colon and rectum.Dis Colon Rectum.2014 Mar;57(3):396-7. doi: 10.1097/DCR.0000000000000084.
Germline mutations in the exonuclease (proofreading) domains of 2 DNA polymerases (POLE and POLD1) have been associated with a dominantly inherited, highly penetrant syndrome of oligo adenomatous polyposis and early-age-of-diagnosis colorectal cancer and endometrial cancer. The loss of proofreading
PMID 24509466

Japanese Journal

歯周ポケットへの線維素溶解酵素と抗生物質の貼用に関する研究(大阪歯科大学大学院歯学研究科博士(歯学)学位論文内容要旨および論文審査結果要旨の公表)

高津兆雄
歯科医学 63(2), 38-39, 2000-06-25
… ロールを目的として, 広く一般臨床に応用されている.そこで, 本研究では, 血液凝固物や線維性滲出液を溶解するフィブリノリジンとDNAあるいはDNA-タンパク複合体に直接作用し, 膿性滲出物の粘稠度を下げるDNAaseを配合した線維素溶解酵素剤であるエレース軟膏^【○!R】を単独およびペリオクリン^【○!R】との併用投与を試み, その効果について臨床的および細菌学的に検索を行った.被験者は, 全身疾患がなく, …
NAID 110001724177

DNA methylation and DNAase-hypersensitive sites in the 5' flanking and transcribed regions of the rat preproenkephalin gene: studies of mediobasal hypothalamus.

FUNABASHI T.
Mol. Cell. Neurosci. 4, 499-509, 1993
NAID 30018784348

Intracellular concentration and structural states of actin in human bladder carcinomas: New indices for malignancy.

TADOKORO SHIGERU
Ｔｈｅ　Ｋｅｉｏ　Ｊｏｕｒｎａｌ　ｏｆ　Ｍｅｄｉｃｉｎｅ 34(1), 47-59, 1985
… Concentration of actin in the cells was determined by DNAase I inhibition assay and by a densitometrical measurement after electrophoretic separation of the cell component. …
NAID 130000872047