Fatty Acid Synthesis

Fatty Acid Synthesis

Fatty acids are used to build more compex molecules, as structural components, and as an energy source, particularly in liver and muscle.

Carbohydrates, proteins, and other molecules in excess of the body's needs can be converted into fatty acids for storage as TAGs. Fatty acid synthesis occurs primarily in the liver, in lactating mammary glands, and to a lesser extend in adiopose tissue.

Fatty acids can be synthesized from Acetyl CoA, derived from the TCA cycle in reverse. Citrate is converted into OAA while generating Acetyl CoA. OAA is converted to malate, which then can become pyruvate.

Acetyl CoA acted on by Acetyl CoA Carboxylase to produce Malonyl CoA, which is then acted on by Fatty Acid Synthase (FAS), a multi-enzyme complex, that sequentially adds 2 carbon units, yielding palmitate. This process requires NADPH, provided by the pentose phosphate pathway.

Malonyl CoA accumulation inhibits fatty acid beta-oxidation.

Fatty acids can then go on to be used in TAG synthesis.

Regulation of Fatty Acid Synthesis

Conversion of Acetyl CoA to Malonyl CoA is increased by insulin and TCA intermediate citrate, and decreased by glucagon and epinephrine and palmitoyl CoA, downstream in the process.

Hormonal Derivitaves of Essential Fatty Acids

Essential fatty acids include linoleic acid (18:2) and alpha-linolenic acid (18:3).

Seed oils are used to produce arachidonic acid, which is then used to produce thromboxanes and prostaglandins.

Fish oils are used to produce eicosapentaenoic acid (EPA), which can also be used to produce other thromboxanes and prostaglandins.