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Understanding Organelle Roles in Fatty Acid Metabolism: Synthesis, Elongation, Desaturation, and Oxidation
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Table 1: Role of organelles in Fatty Acid Synthesis, Elongation, and Desaturation
| Process | Organelle | Function | Key Enzymes/Features |
| De Novo Fatty Acid Synthesis | Cytoplasm | Formation of palmitate (16-carbon saturated fatty acid) from acetyl-CoA and malonyl-CoA. | Acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS) |
| Elongation of Fatty Acids | Endoplasmic Reticulum (ER), Mitochondria | Extends the carbon chain of long-chain fatty acids by adding two-carbon units. | ER elongases, mitochondrial elongation enzymes |
| Desaturation of Fatty Acids | Endoplasmic Reticulum (ER) | Introduces double bonds into fatty acids, forming unsaturated fatty acids. | Stearoyl-CoA desaturase (SCD) and other desaturases |
Table 2: Lipolysis and Fatty Acid Oxidation
| Process | Organelle/Location | Function | Key Enzymes/Features |
| Lipolysis | Cytoplasm (Adipose Tissue) | Breakdown of triglycerides into glycerol and free fatty acids for energy. | Hormone-sensitive lipase (HSL), adipose triglyceride lipase (ATGL) |
| β-Oxidation | Mitochondria | The primary pathway for fatty acid catabolism, involved in breaking fatty acids into acetyl-CoA for ATP production. | Acyl-CoA dehydrogenase, enoyl-CoA hydratase, β-hydroxyacyl-CoA dehydrogenase, thiolase |
| Peroxisomal β-Oxidation | Peroxisomes | Oxidation of very long-chain fatty acids to shorter chains, which are transferred to mitochondria. | Acyl-CoA dehydrogenase/oxidase, catalase (handles H2O2 produced) |
| α-Oxidation | Peroxisomes | Breakdown of branched-chain fatty acids (e.g., phytanic acid) that cannot be processed by β-oxidation. | Phytanoyl-CoA hydroxylase/oxidase |
| ω-Oxidation | Endoplasmic Reticulum (ER) | A minor pathway that oxidizes the terminal carbon (omega carbon) of fatty acids, converting them to dicarboxylic acids. | Cytochrome P450 enzymes |
