Beta-oxidation of polyunsaturated fatty acids with conjugated double bonds. Mitochondrial metabolism of octa-2,4,6-trienoic acid.
The mitochondrial beta-oxidation of octa-2,4,6-trienoic acid was studied with the aim of elucidating the degradation of unsaturated fatty acids with conjugated double bonds. Octa-2,4,6-trienoic acid was found to be a respiratory substrate of coupled rat liver mitochondria, but not of rat heart mitochondria. Octa-2,4,6-trienoyl-CoA, the product of the inner-mitochondrial activation of the acid, was chemically synthesized and its degradation by purified enzymes of beta-oxidation was studied spectrophotometrically and by use of h.p.l.c. This compound is a substrate of NADPH-dependent 2,4-dienoyl-CoA reductase or 4-enoyl-CoA reductase (EC 1.3.1.34), which facilitates its further beta-oxidation. The product obtained after the NADPH-dependent reduction of octa-2,4,6-trienoyl-CoA and one round of beta-oxidation was hex-4-enoyl-CoA, which can be completely degraded via beta-oxidation. It is concluded that polyunsaturated fatty acids with two conjugated double bonds extending from even-numbered carbon atoms can be completely degraded via beta-oxidation because their presumed 2,4,6-trienoyl-CoA intermediates are substrates of 2,4-dienoyl-CoA reductase.
Wang
H Y
HY
Department of Chemistry, City College of the City University of New York, New York 10031.
Schulz
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D000214:Acyl Coenzyme A / Q000378:metabolism; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D044943:Fatty Acid Desaturases / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D008929:Mitochondria, Heart / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism*; D010084:Oxidation-Reduction; D044925:Oxidoreductases Acting on CH-CH Group Donors; D010101:Oxygen Consumption; D051381:Rats; D013379:Substrate Specificity
D000214:Acyl Coenzyme A; D005231:Fatty Acids, Unsaturated; C062198:octa-2,4,6-trienoic acid; D044943:Fatty Acid Desaturases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C100153:2,4-dienoyl-CoA reductase