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| [[Image:Peroxisome.svg|300px|right|thumb|Basic structure of a peroxisome]]
| | The author is known as Cory but he never truly loved that title. After being out-of his job for many years he became an office worker. West Virginia has always been his living area. Todo interiordesign is what him and his family enjoy.<br><br> |
| [[File:Distribution of peroxisomes labelled with a monomeric eqFP611 variant in HEK293 cells during mitosis - pone.0004391.s005.ogv|thumb|300px|Distribution of peroxisomes (white) in [[HEK 293]] cells during [[mitosis]].]]
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| '''Peroxisomes''' {{IPA-all|pɛɜˈɹɒksɪˌsoʊmz}}<ref>{{cite web|title=Peroxisome|url=http://www.merriam-webster.com/dictionary/peroxisome|work=Online DIctionary|publisher=Merriam-Webster|accessdate=19 June 2013}}</ref> (also called '''microbodies''') are [[organelle]]s found in virtually all [[eukaryotic]] cells.<ref name="pmid20124343">{{cite journal | author = Gabaldón T | title = Peroxisome diversity and evolution | journal =Philos Trans R Soc Lond B Biol Sci. | volume = 365 | issue = 1541| pages = 765–73 | year = 2010 | pmid = 20124343 | pmc = 2817229 | doi = 10.1098/rstb.2009.0240 }}</ref> They are involved in the [[catabolism]] of [[very long chain fatty acid]]s, [[branched chain fatty acids]], [[D-amino acids]], [[polyamine]]s, and biosynthesis of [[plasmalogens]], i.e. [[ether phospholipid]]s critical for the normal function of mammalian brains and lungs.<ref name="pmid16756494">{{cite journal | author = Wanders RJ, Waterham HR | title = Biochemistry of mammalian peroxisomes revisited | journal = Annu. Rev. Biochem. | volume = 75 | issue = | pages = 295–332 | year = 2006 | pmid = 16756494 | doi = 10.1146/annurev.biochem.74.082803.133329 | url = }}</ref> They also contain approximately 10% of the total activity of two enzymes in the [[pentose phosphate pathway]], which is important for energy metabolism.<ref name="pmid16756494"/> It is vigorously debated if peroxisomes are involved in [[isoprenoid]] and [[cholesterol]] synthesis in animals.<ref name="pmid16756494"/> Other known peroxisomal functions include the [[glyoxylate cycle]] in germinating seeds ("[[glyoxysomes]]"), [[photorespiration]] in leaves,<ref>{{cite book|author=Evert, R.F.; Eichhorn, S.E.|year=2006|title=Esau's Plant Anatomy: Meristems, Cells, and Tissues of the Plant Body: Their Structure, Function, and Development|publisher=John Wiley & Sons|isbn=9780471738435}}</ref> [[glycolysis]] in [[trypanosomes]] ("[[glycosome]]s"), and [[methanol]] and/or amine oxidation and assimilation in some yeasts.
| | my site - [http://www.svs.cl/institucional/mercados/entidad.php?mercado=V&rut=76034728&grupo=&tipoentidad=RGAGF&row=AAAUvUABfAAAAxXAAr&vig=VI&control=svs&pestania=47 jaun pablo schiappacasse canepa] |
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| Peroxisomes were identified as organelles by the Belgian cytologist [[Christian de Duve]] in 1967<ref name="pmid4389648">{{cite journal | author = de Duve C | title = The peroxisome: a new cytoplasmic organelle | journal = Proc. R. Soc. Lond., B, Biol. Sci. | volume = 173 | issue = 30 | pages = 71–83 | year = 1969 | pmid = 4389648 | doi = 10.1098/rspb.1969.0039 }}</ref> after they had been first described by a Swedish doctoral student, J. Rhodin in 1954.<ref name="Rhodin_1954">{{cite journal | author = Rhodin, J | title = Correlation of ultrastructural organization and function in normal and experimentally changed proximal tubule cells of the mouse kidney | journal = Doctorate Thesis. Karolinska Institutet, Stockholm | volume = | issue = | pages = | year = 1954 | pmid = | doi = }}</ref>
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| == Metabolic functions ==
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| A major function of the peroxisome is the breakdown of very long chain [[fatty acids]] through [[beta-oxidation]]. In animal cells, the very long fatty acids are converted to medium chain fatty acids, which are subsequently shuttled to mitochondria where they are eventually broken down to carbon dioxide and water. In yeast and plant cells, this process is exclusive for the peroxisomes.<ref name="alberts">{{cite book | author = Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P | authorlink = | editor = | others = | title = Molecular Biology of the Cell | edition = Fourth | language = | publisher = Garland Science | location = New York | year = 2002 | origyear = | pages = | quote = | isbn = 0-8153-3218-1 | chapter = Chapter 12: Peroxisomes | doi = | url = http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mboc4.section.2194 | accessdate = }}</ref>
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| The first reactions in the formation of [[plasmalogen]] in animal cells also occur in peroxisomes. Plasmalogen is the most abundant phospholipid in [[myelin]]. Deficiency of plasmalogens causes profound abnormalities in the myelination of [[neuron|nerve cells]], which is one reason why many [[peroxisomal disorders]] affect the nervous system.<ref name="alberts"/> Peroxisomes also play a role in the production of [[bile]] acids important for the absorption of fats and fat-soluble vitamins, such as vitamins A and K. Skin disorders are features of genetic disorders affecting peroxisome function as a result.
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| Peroxisomes contain oxidative [[enzyme]]s, such as [[catalase]], [[D-amino acid oxidase]], and [[uric acid oxidase]].<ref name="pmid1334030">{{cite journal | author = del Río LA, Sandalio LM, Palma JM, Bueno P, Corpas FJ | title = Metabolism of oxygen radicals in peroxisomes and cellular implications | journal = Free Radic. Biol. Med. | volume = 13 | issue = 5 | pages = 557–80 | year = 1992 | pmid = 1334030 | doi = 10.1016/0891-5849(92)90150-F }}</ref> However the last enzyme is absent in humans, explaining the disease known as [[gout]], caused by the accumulation of uric acid. Certain enzymes within the peroxisome, by using molecular oxygen, remove hydrogen atoms from specific organic substrates (labeled as R), in an oxidative reaction, producing [[hydrogen peroxide]] (H<sub>2</sub>O<sub>2</sub>, itself toxic):
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| :<math>\mathrm{RH}_\mathrm{2} + \mathrm{O}_\mathrm{2} \rightarrow \mathrm{R }+ \mathrm{H}_2\mathrm{O}_2</math>
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| Catalase, another peroxisomal enzyme, uses this H<sub>2</sub>O<sub>2</sub> to oxidize other substrates, including [[phenols]], [[formic acid]], [[formaldehyde]], and [[alcohol]], by means of the peroxidation reaction:
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| :<math>\mathrm{H}_2\mathrm{O}_2 + \mathrm{R'H}_2 \rightarrow \mathrm{R'} + 2\mathrm{H}_2\mathrm{O}</math>, thus eliminating the poisonous hydrogen peroxide in the process.
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| This reaction is important in liver and kidney cells, where the peroxisomes detoxify various toxic substances that enter the blood. About 25% of the [[ethanol]] humans drink is oxidized to [[acetaldehyde]] in this way.<ref name="alberts">{{cite book | author = Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P | authorlink = | editor = | others = | title = Molecular Biology of the Cell | edition = Fourth | language = | publisher = Garland Science | location = New York | year = 2002 | origyear = | pages = | quote = | isbn = 0-8153-3218-1 | chapter = Chapter 12: Peroxisomes | doi = | url = http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mboc4.section.2194 | accessdate = }}</ref> In addition, when excess H<sub>2</sub>O<sub>2</sub> accumulates in the cell, catalase converts it to H<sub>2</sub>O through this reaction:
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| :<math>2\mathrm{H}_2\mathrm{O}_2 \rightarrow 2\mathrm{H}_2\mathrm{O} + \mathrm{O}_2</math>
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| In higher plants, peroxisomes contain also a complex battery of antioxidative enzymes such as superoxide dismutase, the components of the [[ascorbate-glutathione cycle]], and the NADP-dehydrogenases of the pentose-phosphate pathway. It has been demonstrated that peroxisomes generate [[superoxide]] (O<sub>2</sub><sup>•-</sup>) and [[nitric oxide]] (<sup>•</sup>NO) radicals.<ref name="pmid11286918">{{cite journal | author = Corpas FJ, Barroso JB, del Río LA | title = Peroxisomes as a source of reactive oxygen species and nitric oxide signal molecules in plant cells | journal = Trends Plant Sci. | volume = 6 | issue = 4 | pages = 145–50 |date=April 2001 | pmid = 11286918 | doi = 10.1016/S1360-1385(01)01898-2 }}</ref><ref name="pmid15347796">{{cite journal | author = Corpas FJ, Barroso JB, Carreras A, Quirós M, León AM, Romero-Puertas MC, Esteban FJ, Valderrama R, Palma JM, Sandalio LM, Gómez M, del Río LA | title = Cellular and subcellular localization of endogenous nitric oxide in young and senescent pea plants | journal = Plant Physiol. | volume = 136 | issue = 1 | pages = 2722–33 |date=September 2004 | pmid = 15347796 | pmc = 523336 | doi = 10.1104/pp.104.042812 }}</ref>
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| The peroxisome of plant cells is polarised when fighting fungal penetration. Infection causes a [[glucosinolate]] molecule to play an antifungal role to be made and delivered to the outside of the cell through the action of the peroxisomal proteins (PEN2 and PEN3).<ref name="pmid19095900">{{cite journal | author = Bednarek P, Pislewska-Bednarek M, Svatos A, Schneider B, Doubsky J, Mansurova M, Humphry M, Consonni C, Panstruga R, Sanchez-Vallet A, Molina A, Schulze-Lefert P | title = A glucosinolate metabolism pathway in living plant cells mediates broad-spectrum antifungal defense | journal = Science | volume = 323 | issue = 5910 | pages = 101–6 |date=January 2009 | pmid = 19095900 | doi = 10.1126/science.1163732 | url = }}</ref>
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| == Peroxisome assembly ==
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| Peroxisomes can be derived from the [[endoplasmic reticulum]] and replicate by fission.<ref name="pmid16009135">{{cite journal | author = Hoepfner D, Schildknegt D, Braakman I, Philippsen P, Tabak HF | title = Contribution of the endoplasmic reticulum to peroxisome formation | journal = Cell | volume = 122 | issue = 1 | pages = 85–95 | year = 2005 | pmid = 16009135 | doi = 10.1016/j.cell.2005.04.025 }}</ref> Peroxisome matrix proteins are translated in the cytoplasm prior to import. Specific amino acid sequences (PTS or [[peroxisomal targeting signal]]) at the ''[[C-terminus]]'' (PTS1) or ''[[N-terminus]]'' (PTS2) of peroxisomal matrix proteins signals them to be imported into the organelle. There are at least 32 known peroxisomal proteins, called [[peroxin]]s,<ref name="pmid17050007">{{cite journal | author = Saleem RA, Smith JJ, Aitchison JD | title = Proteomics of the Peroxisome | journal = Biochim. Biophys. Acta | volume = 1763 | issue = 12 | pages = 1541–51 | year = 2006 | pmid = 17050007 | doi = 10.1016/j.bbamcr.2006.09.005| pmc = 1858641 }}</ref> which participate in the process of peroxisome assembly. Proteins do not have to unfold to be imported into the peroxisome. The protein receptors, the peroxins ''[[PEX5]]'' and ''[[PEX7]]'', accompany their cargoes (containing a PTS1 or a PTS2 amino acid sequence, respectively) all the way into the peroxisome where they release the cargo and then return to the [[cytosol]] - a step named ''recycling''. A model describing the import cycle is referred to as the ''extended shuttle mechanism''.<ref name="pmid11336669">{{cite journal | author = Dammai V, Subramani S | title = The human peroxisomal targeting signal receptor, Pex5p, is translocated into the peroxisomal matrix and recycled to the cytosol | journal = Cell | volume = 105 | issue = 2 | pages = 187–96 |date=April 2001 | pmid = 11336669 | doi = }}</ref> There is now evidence that ATP hydrolysis is required for the recycling of receptors to the [[cytosol]]. Also, [[ubiquitination]] appears to be crucial for the export of PEX5 from the peroxisome, to the cytosol.
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| == Associated medical conditions ==
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| [[Peroxisomal disorders]] are a class of medical conditions that typically affect the human nervous system as well as many other organ systems. Two common examples are [[X-linked]] [[adrenoleukodystrophy]] and [[peroxisome biogenesis disorders]].<ref name="pmid12740827">{{cite journal | author = Depreter M, Espeel M, Roels F | title = Human peroxisomal disorders | journal = Microsc. Res. Tech. | volume = 61 | issue = 2 | pages = 203–23 |date=June 2003 | pmid = 12740827 | doi = 10.1002/jemt.10330 | url = }}</ref><ref name="Roels_1995">{{cite journal | author = Roels F, De Bie S, Schutgens RBH, Besley GTN | title = Diagnostic laboratory methods in peroxisomal disorders | journal = Journal of Inherited Metabolic Disease | year = 1995 | volume = 18 | issue = Supplement 1 | pages = 1–229 | url = http://www.springerlink.com/content/0141-8955/18/s1/ }}</ref>
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| == Genes ==
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| ''PEX'' genes encode the protein machinery ("peroxins") required for proper peroxisome assembly, as described above. Membrane assembly and maintenance requires three of these (peroxins 3, 16, and 19) and may occur without the import of the matrix (lumen) enzymes. Proliferation of the organelle is regulated by Pex11p.
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| Genes that encode peroxin proteins include: [[PEX1]], [[PEX2]] - [[PXMP3]], [[PEX3]], [[PEX5]], [[PEX6]], [[PEX7]], [[PEX10]], [[PEX11A]], [[PEX11B]], [[PEX11G]], [[PEX12]], [[PEX13]], [[PEX14]], [[PEX16]], [[PEX19]], [[PEX26]], [[PEX28]], [[PEX30]], and [[PEX31]].
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| == Evolutionary origins ==
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| The protein content of peroxisomes varies across species, but the presence of proteins common to many species has been used to suggest an [[Endosymbiotic theory|endosymbiotic]] origin; that is, peroxisomes evolved from bacteria that invaded larger cells as parasites, and very gradually evolved a symbiotic relationship.<ref name="pmid3916321">{{cite journal | author = Lazarow PB, Fujiki Y | title = Biogenesis of peroxisomes | journal = Annu. Rev. Cell Biol. | volume = 1 | issue = | pages = 489–530 | year = 1985 | pmid = 3916321 | doi = 10.1146/annurev.cb.01.110185.002421 }}</ref> However, this view has been challenged by recent discoveries.<ref name="pmid17506702">{{cite journal | author = Fagarasanu A, Fagarasanu M, Rachubinski, RA | title = Maintaining peroxisome populations: a story of division and inheritance| journal = Annu. Rev. Cell Dev. Biol. | volume = 23 | issue = | pages = 321–344| year = 2007 | pmid = 17506702 | doi = 10.1146/annurev.cellbio.23.090506.123456}}</ref> For example, peroxisome-less mutants can restore peroxisomes upon introduction of the wild-type gene.
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| Two independent evolutionary analyses of the peroxisomal [[proteome]] found homologies between the peroxisomal import machinery and the [[Endoplasmic Reticulum Associated Protein Degradation|ERAD]] pathway in the [[endoplasmic reticulum]],<ref name="pmid16452116">{{cite journal | author = Schlüter A, Fourcade S, Ripp R, Mandel JL, Poch O, Pujol A | title = The evolutionary origin of peroxisomes: an ER-peroxisome connection | journal = Mol Biol Evol | volume = 23 | issue = 4| pages = 838–45 | year = 2006 | pmid = 16452116 | doi = 10.1093/molbev/msj103 }}</ref><ref name="pmid16556314">{{cite journal | author = Gabaldón T, Snel B, van Zimmeren F, Hemrika W, Tabak H, Huynen MA | title = Origin and evolution of the peroxisomal proteome | journal = Biol. Direct | volume = 1 | issue = | pages = 8 | year = 2006 | pmid = 16556314 | pmc = 1472686 | doi = 10.1186/1745-6150-1-8 }}</ref> along with a number of metabolic enzymes that were likely recruited from the [[mitochondria]].<ref name="pmid16556314"/> Recently, it has been suggested that the peroxisome may have had an [[Actinobacteria|actinobacterial]] origin,<ref name="pmid19818387">{{cite journal | author = Duhita, et al | title = The origin of peroxisomes: The possibility of an actinobacterial symbiosis | journal = Gene | year = 2009 | pmid = 19818387 | doi = 10.1016/j.gene.2009.09.014 | last2 = Le | first2 = HA | last3 = Satoshi | first3 = S | last4 = Kazuo | first4 = H | last5 = Daisuke | first5 = M | last6 = Takao | first6 = S | volume = 450 | issue = 1–2 | pages = 18–24 }}</ref> however, this is controversial.<ref name="pmid20600706">{{cite journal | author = Gabaldón T, Capella-Gutiérrez S | title = Lack of phylogenetic support for a supposed actinobacterial origin of peroxisomes | journal = Gene | volume = 465 | issue = 1–2 | pages = 61–5 |date=October 2010 | pmid = 20600706 | doi = 10.1016/j.gene.2010.06.004 | url = }}</ref>
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| == Other related organelles ==
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| Other organelles of the [[microbody]] family related to peroxisomes include [[glyoxysome]]s of [[plant]]s and [[filamentous fungi]], [[glycosome]]s of [[kinetoplastid]]s<ref name="pmid1447292">{{cite journal | author = Blattner J, Swinkels B, Dörsam H, Prospero T, Subramani S, Clayton C | title = Glycosome assembly in trypanosomes: variations in the acceptable degeneracy of a COOH-terminal microbody targeting signal | journal = J. Cell Biol. | volume = 119 | issue = 5 | pages = 1129–36 |date=December 1992 | pmid = 1447292 | pmc = 2289717 | doi = 10.1083/jcb.119.5.1129 | url = }}</ref> and [[Woronin body|Woronin bodies]] of [[filamentous fungi]].
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| == References ==
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| {{reflist|35em}}
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| == Further reading ==
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| {{refbegin}}
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| * {{cite journal | author = Mateos RM, León AM, Sandalio LM, Gómez M, del Río LA, Palma JM | title = Peroxisomes from pepper fruits (''Capsicum annuum'' L.): purification, characterisation and antioxidant activity | journal = J. Plant Physiol. | volume = 160 | issue = 12 | pages = 1507–16 |date=December 2003 | pmid = 14717445 | doi = 10.1078/0176-1617-01008 }}
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| {{refend}}
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| ==External links==
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| {{wikiversity|Peroxisomes|at-link=Topic:Cell Biology|at=The Department of Cell Biology}}
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| {{Commonscat|Peroxisomes}}
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| *[http://www.peroxisomeDB.org PeroxisomeDB: Peroxisome-Database]
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| *[http://www.peroxisomekb.nl PeroxisomeKB: Peroxisome Knowledge Base]
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| {{NCBI-scienceprimer}}
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| {{InterPro content|IPR006708}}
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| {{organelles}}
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| {{Peroxisomal proteins}}
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| [[Category:Organelles]]
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| [[Category:Metabolism]]
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