The biosynthesis of unsaturated fatty acids begins with palmitic acid interacting with ATP and Coenzyme A through an acyl-CoA synthetase resulting in the release of AMP, diphosphate and palmitoyl-CoA. This compound then enters the cycle of unsaturated fatty acid elongation This cycle starts with the acyl-CoA reacting with a hydrogen ion and a malonyl-CoA through a 3-oxo-stearoyl-CoA synthase resulting in the release of a coenzyme A, a carbon dioxide molecule and a 3-oxoacyl-CoA. The 3-oxoacyl-CoA then reacts with a hydrogen ion and an NADPH through a 3-oxoacyl-CoA reductase resulting in the release of an NADP and a (3R)-3-hydroxy-acyl-CoA. The resulting compound then reacts with a trans-2-enoyl-CoA hydratase 2 resulting in the release of water and trans-2,3-dehydroacyl-CoA. This compound then reacts with a hydrogen ion and a NADPH through a enoyl-CoA reductase resulting in the release of a NADP and a new acyl-CoA. The cycle goes from palmitoyl-CoA-->stearoyl-CoA-->eicosanoyl-CoA-->docosanoyl-CoA-->tetracosanoyl-CoA-->hexacosanoyl-CoA. The long chain fatty acids are then incorporated into the sphingolipid pathway. The long chain fatty acid reacts with a phytosphingosine through a ceramide synthase resulting in the release of a hydrogen ion, a coenzyme A and a N-acyl-phytosphinganine.

Biosynthesis of Unsaturated Fatty Acids (Tetracosanoyl-CoA) References