Biochemistry of Fatty Acid Metabolism

Dehydrogenation

• Dehydrogenation converts -OH group on beta carbon into a C=O double bond, making the molecule more reactive.
• Involves removal of hydrogen atoms from a specific place in a molecule, transferring them to FAD+ and forming a double bond between neighboring carbon atoms.

Acetyl-CoA

• Central in energy production, entering the citric acid cycle to generate energy.
• Forms when fatty acid chain is broken down into smaller pieces, producing energy in citric acid cycle.
• Can be converted from citrate, which is formed in mitochondria, and then transported into cytosol for fatty acid synthesis.

Fatty Acid Synthesis

• Occurs in cytosol, converting acetyl-CoA into malonyl-CoA (a 3-carbon molecule) and then adding more acetyl groups to build a longer fatty acid chain.
• Involves the combination of acetyl-CoA and malonyl-CoA to form a longer fatty acid chain.

Fatty Acid Breakdown

• Fatty acids are attached to CoA, forming acetyl-CoA, which is then broken down into smaller pieces, each with 2 carbon atoms, to produce energy.
• Breaking down fatty acids generates acetyl-CoA, which enters the citric acid cycle to produce high-energy molecules used for ATP.
• Fatty acids are transported into mitochondria by attaching to carnitine, and then removed to form acetyl-CoA, which is broken down for energy.

Acyl-CoA vs Acetyl-CoA

• Acyl-CoA has a longer carbon chain and is involved in the metabolism of fatty acids.
• Acetyl-CoA contains two carbon acetyls and is central in energy production, entering the citric acid cycle to generate energy.

4 Steps in Fatty Acid Breakdown

Hydration

• Water is added to the double bond formed in dehydrogenation, changing the double bond to a single bond and attaching a hydroxyl group to the beta carbon.

Other Key Points

• DHAP is formed from breaking down fructose 1-phosphate.