peroxisome

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Peroxisome

An intracellular organelle found in all eukaryotes except the archezoa (original lifeforms). In electron micrographs, peroxisomes appear round with a diameter of 0.1–1.0 micrometer, although there is evidence that in some mammalian tissues peroxisomes form an extensive reticulum (network). They contain more than 50 characterized enzymes and perform many biochemical functions, including detoxification. See Cell organization, Enzyme

Peroxisomes are important for lipid metabolism. In humans, the β-oxidation of fatty acids greater than 18 carbons in length occurs in peroxisomes. In yeast, all fatty acid β-oxidation occurs in peroxisomes. Peroxisomes contain the first two enzymes required for the synthesis of plasmalogens. Peroxisomes also play important roles in cholesterol and bile acid synthesis, purine and polyamine catabolism, and prostaglandin metabolism. In plants, peroxisomes are required for photorespiration. See Lipid metabolism, Photorespiration

A number of recessively inherited peroxisomal disorders have been described and grouped into three categories. Group I is the most severe and is characterized by a general loss of peroxisomal function. Many of the enzymes normally localized to the peroxisome are instead found in the cytosol. Among the diseases found in group I are Zellweger syndrome, neonatal adrenoleukodystrophy, and infantile Refsum disease. Patients with these disorders usually die within the first years after birth and exhibit neurological and hepatic (liver) dysfunction, along with craniofacial dysmorphism (malformation of the cranium and the face). Groups II and III peroxisomal disorders are characterized by a loss of peroxisomal function less severe than in group I.

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.

peroxisome

[pə′räk·sə‚sōm]
(cell and molecular biology)
Any of a subclass of microbodies that contain at least four enzymes involved in the metabolism of hydrogen peroxide.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Stavru et al., "Diverse intracellular pathogens activate type III interferon expression from peroxisomes," Nature Immunology, vol.
The researchers moved peroxisomes around in the cell using a sophisticated laboratory technique, with the same result.
The oxidative degradation of fatty acids takes place in peroxisomes and mitochondria (Figure 1).
Genetic heterogeneity consisting of 14 CGs has been identified in PBDs by cell-fusion CG analysis using fibroblast cell lines derived from PBD patients (5), (20), (25)-(27) (Table 3), where the primary cause for PBDs was revealed to be the impaired biogenesis of peroxisomes. (5),(20)
Anti-inflammatory effects of PEA have been associated with peroxisome proliferator-activated receptor-(PPAR-)a activation [18], a nuclear receptor fundamental in the control of inflammatory responses, and expressed in various cells of the immune system [19, 20].
BACKGROUND: Trichloroacetic acid, an oxidative metabolite of trichloroethylene (TRI), is a ligand of the peroxisome proliferator-activated receptor [alpha] (PPAR) [alpha], which is involved in lipid homeostasis and anti-inflammation.
Mice engineered to direct catalase to its usual place, in peroxisomes, showed only a modest increase in life span.
These data indicate that [beta]-oxidation of C24:0 to C16:0 takes place exclusively in peroxisomes and not in mitochondria.
Peroxisomes function in various metabolic activities, including lipid metabolism.
Peroxisome proliferator-activated receptors (PPARs), a subfamily of nuclear receptors, play a crucial role in regulating insulin sensitivity and may serve as potential therapeutic targets for AD.

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