Fatty acids are essential components of lipids, including triglycerides, phospholipids, and cholesterol esters. These molecules play crucial roles in energy storage, cell membrane structure, and signalling processes in the body. The reactions involving fatty acids are diverse and involve various metabolic pathways. Here’s a detailed note on rich acid reactions:
1. Fatty Acid Synthesis (De Novo Lipogenesis):
Process: De novo lipogenesis is the biosynthesis of fatty acids from acetyl-CoA and malonyl-CoA, primarily occurring in the liver. This process involves a series of enzymatic reactions catalysed by fatty acid synthase (FAS).
Key Reactions: Condensation of acetyl-CoA and malonyl-CoA, reduction, dehydration, and a second reduction, repeating cyclically to extend the fatty acid chain.
Significance: This pathway synthesizes fatty acids, which are later incorporated into triglycerides for energy storage, and is essential.
2. β-Oxidation (Fatty Acid Catabolism):
Process: β-oxidation is the breakdown of fatty acids into acetyl-CoA molecules, which enter the citric acid cycle for energy production.
Key Reactions: The fatty acid cleaves at the beta-carbon, producing acetyl-CoA by successively removing two-carbon fragments.
Significance: This process occurs in the mitochondria and is crucial for energy release during fasting or increased energy demand.
3. Fatty Acid Activation (Fatty Acyl-CoA Synthesis):
Process: Fatty acyl-CoA synthetase catalyzes a two-step process, activating fatty acids by attaching CoA to form fatty acyl-CoA.
Key Reactions: First, hydrolyzing ATP to AMP releases pyrophosphate. Next, linking the activated fatty acid to CoA occurs.
Significance: To enter β-oxidation or be used in synthesizing complex lipids, fatty acids require activation.
4. Esterification to Form Triglycerides:
Process: Fatty acids are esterified to glycerol to form triglycerides (triacylglycerols).
Key Reactions: Fatty acids react with glycerol, releasing water molecules and forming ester bonds.
Significance: During periods of energy demand, adipose tissue mobilizes triglycerides, which serve as the primary form of stored energy.
5. Phospholipid Synthesis:
Process: Phospholipids are synthesised by attaching a phosphate group to the glycerol backbone, replacing one of the fatty acid chains.
Key Reactions: Enzymes such as phospholipase and phosphatase add the phosphate group to diacylglycerol.
Significance: Phospholipids are vital components of cell membranes, contributing to their structure and function.
6. Fatty Acid Desaturation:
Process: Desaturation involves the introduction of double bonds into fatty acids, increasing their unsaturation.
Key Reactions: Enzymes like desaturases introduce double bonds into the fatty acid chain.
Significance: Desaturation is essential for synthesising polyunsaturated fatty acids, which play crucial roles in cell membrane fluidity and signalling.
7. Lipolysis:
Process: Lipolysis is the hydrolysis of triglycerides into fatty acids and glycerol, releasing stored energy.
Key Reactions: Enzymes called lipases catalyse the hydrolysis of ester bonds in triglycerides.
Significance: Lipolysis is crucial during fasting or increased energy demands, fueling fatty acids.
Fatty acids participate in these reactions to regulate energy metabolism, maintain cellular structure, and contribute to various physiological functions. The intricate balance between anabolism and catabolism of fatty acids is essential for overall metabolic homeostasis.
