Understanding Organelle Roles in Fatty Acid Metabolism: Synthesis, Elongation, Desaturation, and Oxidation

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

 

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