BMS1011: Lipid Synthesis and Oxidation

Fatty Acid Synthesis

• Fatty acid synthesis begins with the formation of malonyl-CoA from acetyl-CoA, CO2, and ATP
• The process is catalyzed by the fatty acid synthase enzyme and occurs in the cytosol
• Elongation of fatty acid chain involves condensation, reduction, dehydration, and reduction reactions
• The overall synthesis of palmitate (16C fatty acid) requires 7 acetyl-CoA, 7 CO2, 7 ATP, and 14 NADPH
• The process involves the transfer of acetyl-CoA and malonyl-CoA, and the reduction of β-keto group using NADPH
• Sources of NADPH include malic enzyme and the pentose phosphate pathway
• Fatty acid synthesis is regulated and distinct from fatty acid breakdown, requiring acetyl-CoA, NADPH, and malonyl-CoA as key precursors

Triacylglycerol Synthesis

• Triacylglycerol synthesis involves the formation of triacylglycerol from fatty acids and glycerol
• Synthesis and degradation of triacylglycerol are tightly regulated
• The triacylglycerol cycle helps to re-synthesize triacylglycerols

Cholesterol Synthesis

• Cholesterol synthesis involves the synthesis of cholesterol from acetyl-CoA
• Cholesterol is transported in the blood as lipoproteins
• Chylomicrons transport cholesterol and triacylglycerol from the intestines to the liver
• VLDL transports cholesterol and triacylglycerol from the liver to tissues
• LDL delivers cholesterol to tissues
• HDL removes cholesterol from peripheral tissues

Understand the significance of lipogenesis and compare lipid oxidation with reductive biosynthesis in this topic on lipid synthesis, triglycerides, and cholesterol.