Participation of peroxisomes in lipid biosynthesis in the harderian gland of guinea pig.
Peroxisomal enzyme activities in the guinea-pig harderian gland, which has a unique lipid composition, were studied. Activities of catalase, acyl-CoA oxidase and the cyanide-insensitive acyl-CoA beta-oxidation system in this tissue were comparable with those in rat liver. The activities of dihydroxyacetone phosphate acyltransferase (DHAPAT, EC 2.3.1.42) and alkyl-DHAP synthase (EC 2.5.1.26) were appreciable, and the distributions of both activities were consistent with that of sedimentable catalase activity. Glycerol-3-phosphate acyltransferase (GPAT, EC 2.3.1.15), which is localized in both microsomes (microsomal fractions) and mitochondria in the rat liver, was a peroxisomal enzyme in the harderian gland, though the activity was only about one-tenth of the DHAPAT activity. These enzymes had different pH profiles and substrate specificity. The existence of high activities of enzymes of the acyl-DHAP pathway in peroxisomes suggests the physiological significance of peroxisomes in the biosynthesis of glycerol ether phospholipid and 1-alkyl-2,3-diacylglycerol in the guinea-pig harderian gland.
Horie
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S
Department of Clinical Biochemistry, Tokyo College of Pharmacy, Japan.
Suga
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T
D000217:Acyltransferases / Q000378:metabolism; D000818:Animals; D002333:Carnitine Acyltransferases / Q000378:metabolism; D002332:Carnitine O-Acetyltransferase / Q000378:metabolism; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000378:metabolism; D006168:Guinea Pigs; D006243:Harderian Gland / Q000201:enzymology* / Q000648:ultrastructure; D007765:Lacrimal Apparatus / Q000201:enzymology*; D008055:Lipids / Q000096:biosynthesis*; D008297:Male; D008830:Microbodies / Q000201:enzymology*
D008055:Lipids; D000217:Acyltransferases; D002333:Carnitine Acyltransferases; C030162:carnitine octanoyltransferase; D005992:Glycerol-3-Phosphate O-Acyltransferase; C020051:glycerone-phosphate O-acyltransferase; D002332:Carnitine O-Acetyltransferase