Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04040 (Catalase)
 3,577 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Peroxisomes were isolated from rat liver by pelleting a light mitochondrial (L) fraction over a 30% (w/v) Metrizamide layer. Peroxisomes were recovered as a loose pellet from the bottom of the tube and the purity of the peroxisomal fraction was calculated to be about 90%. The characteristics of dihydroxyacetone-phosphate acyltransferase (DHAP-AT) in the light mitochondrial fraction and the purified peroxisomal fraction were compared. The behaviour of the enzyme in the two fractions was very similar, except for the effect of sodium fluoride, which stimulated the activity in the L fraction 5-10-fold and in the peroxisomal fraction only 1.6-fold. This difference could be explained by the action of fluoride-sensitive acid phosphatases present in the L fraction that dephosphorylate palmitoyl-coenzyme A, a substrate for DHAP-AT. The localizations of DHAP-AT and alkyldihydroxyacetone-phosphate synthase in the rat liver peroxisomal membrane were studied. It is shown that in intact peroxisomes, DHAP-AT and alkyl-DHAP synthase are resistant to proteolytic inactivation by trypsin, as is fatty acid beta-oxidation activity, which served as a marker for the intactness of the peroxisomal membrane. Catalase was found not to be a suitable marker to assess peroxisome intactness in view of its relative insensitivity to trypsin. In 1-lauroyllysophosphatidylcholine-permeabilized peroxisomes, DHAP-AT, alkyl-DHAP synthase and beta-oxidation activities were rapidly inactivated by trypsin. It is concluded that in rat liver peroxisomes, at least the active sites of the integral membrane proteins DHAP-AT and alkyl-DHAP synthase are localized exclusively at the inner surface of the peroxisomal membrane.
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PMID:Rat liver dihydroxyacetone-phosphate acyltransferase: enzyme characteristics and localization studies. 317 24

In order to explore the potential value of Chinese hamster ovary (CHO) cells for the isolation of peroxisomal mutants defective in the peroxisomal fatty acid oxidation system, some characteristics of their peroxisomes were studied. Catalase was detected biochemically and histochemically in peroxisome-like particles in cells or in subcellular fractions prepared by differential centrifugation or isopyknic equilibrium in Percoll or Metrizamide with catalase in the high density fractions of the isopyknic equilibrium gradients. By oxidation system, exhibited an unusually high specific activity, 2.46 +/- 1.09 mU/mg protein, in CHO cell homogenates, a value comparable to that of rat liver. This enzyme copurifies with catalase in the high density fractions of the isopycnic equilibrium gradients. By analogy with other cell types and from the ultrastructural analysis, it is concluded that these enzymes are contained in peroxisomes. These findings support the value of CHO cells for studies of peroxisomal function and organization.
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PMID:Characterization of peroxisomes in Chinese hamster ovary cells in culture. 405 30