Do rat hepatic microsomes contain multiple NADPH-supported fatty acid chain elongation pathways or a single pathway?
[2-14C]-trans-2-hexadecenoyl CoA (16:1) and [2-14C]-trans-2-cis-8,11,14-eicosatetraenoyl CoA (20:4) were chemically synthesized and employed as competitive substrates for the liver microsomal trans-2-enoyl CoA reductase component of the fatty acid chain elongation system. Both 7.5 microM and 15 microM 20:4 competitively inhibited the reduction of 16:1 CoA to palmitoyl CoA. In addition, the reduction of both substrates was identically inhibited to the same extent by the acetylenic derivative, dec-2-ynoyl CoA. Furthermore, trypsin, chymotrypsin and subtilisin inhibited trans-2-enoyl CoA reductase activity when three different substrates were employed--16:1, 20:4 and trans-2-cis-11-octadecadienoyl CoA (18:2). These results are consistent with the hypothesis of multiple condensing enzymes connected to a single elongation pathway.
D044944:Acyl-CoA Dehydrogenases; D000818:Animals; D044943:Fatty Acid Desaturases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014357:Trypsin / Q000494:pharmacology
D005227:Fatty Acids; D044943:Fatty Acid Desaturases; D044944:Acyl-CoA Dehydrogenases; C100154:acyl-CoA dehydrogenase (NADP+); D014357:Trypsin