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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.


(cell and molecular biology)
Any of a subclass of microbodies that contain at least four enzymes involved in the metabolism of hydrogen peroxide.
References in periodicals archive ?
Differential expression of peroxisome proliferator-activated receptors (PPARs): Tissue distribution of PPARalpha, -beta, and -gamma in the adult rat.
From molecular action to physiological outputs: peroxisome proliferator-activated receptors are nuclear receptors at the crossroads of key cellular functions.
1] Nonstandard abbreviations: hepcidinl, mouse hepcidin antimicrobial peptide 1; PGC-1[alpha], peroxisome proliferator-activated receptor [gamma] coactivator 1[alpha]; HNF4[alpha], hepatocyte nuclear factor 4[alpha]; FOXO1, forkhead box O1 protein.
One possibility as to why ibuprofen may have this effect against Parkinson's disease is that it may target a certain receptor in the brain called the peroxisome proliferator-activated receptor y (PPARy).
Peroxisome proliferators activated receptor-gamma (PPAR-[gamma]) is a ligand activated transcription factor and its activity is regulated by several natural ligands, including fatty acids and eicosanoids (7).
Ibuprofen's protective effect may be due to the drug targeting a brain protein called the peroxisome proliferator-activated receptory, said the researchers.
They upregulate peroxisome proliferator-activated receptor-alpha, which increases fatty acid oxidation from peroxisomes and mitochondria.
The most severe of a group of four related diseases called peroxisome biogenesis disorders, it affects how the body metabolises particular substances in the blood and organ tissues.
Citroflex B-6 does not induce hepatic peroxisome proliferation.
Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that regulate multiple physiological processes, including inflammation, development, and lipid metabolism.
The FDA's recent approval of muraglitazar (Pargluva)--the new peroxisome proliferator-activated receptor-[alpha] and PPAR-[gamma] agonist--in spite of evidence suggesting a doubling of cardiovascular events, along with Dr.

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