Peroxisomal retroconversion of docosahexaenoic acid (22:6(n-3)) to eicosapentaenoic acid (20:5(n-3)) studied in isolated rat liver cells.
Retroconversion of docosahexaenoic acid (DHA, 22:6(n-3)) to eicosapentaenoic acid (EPA, 20:5(n-3)) was studied in isolated rat liver cells. 20% of the substrate was retroconverted to EPA in control cells by one cycle of beta-oxidation probably with delta 4 enoyl CoA reductase and delta 3, delta 2 enoyl CoA isomerase as auxiliary enzymes. This conversion was not stimulated by (-)-carnitine and was not inhibited by the addition of (+)-decanoylcarnitine. In hepatocytes from fasted rats little EPA was formed from DHA. These results strongly suggest that the retroconversion of DHA to EPA is a peroxisomal function. Retroconverted EPA, produced from DHA was rapidly incorporated in triacylglycerol, the phosphatidylcholine and phosphatidyletanolamine fractions. During longer incubation time EPA was partly removed from the phospholipid fractions, chain-elongated to 22:5(n-3) and incorporated in the triacylglycerol fraction.
Grønn
M
M
Institute of Clinical Biochemistry, University of Oslo, Rikshospitalet, Norway.
Christensen
E
E
Hagve
T A
TA
Christophersen
B O
BO
D000818:Animals; D002331:Carnitine / Q000031:analogs & derivatives / Q000494:pharmacology; D002994:Clofibrate / Q000494:pharmacology; D004281:Docosahexaenoic Acids / Q000378:metabolism*; D015118:Eicosapentaenoic Acid / Q000378:metabolism*; D005215:Fasting; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008830:Microbodies / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values
C002893:decanoylcarnitine; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid; D002994:Clofibrate; D002331:Carnitine