2. Fatty acids :
• Fatty acids are long chain aliphatic carboxylic acids
found in natural fats and oils and also a component of
membrane phospholipids and glycolipids.
• The fatty acids are the major source of energy during
metabolism.
• For the production of fatty acids, acetyl CoA produced
in mitochondria is transported across the organelle’s
membrane into the cytosol.
• Acetyl CoA cannot pass through the membrane and hence
it is transported as Citrate.
3. Fatty Acid Synthase
• All the reactions of biosynthesis of fatty acids are catalysed by a multienzyme complex, the
fatty acid synthase.
• The fatty acid synthase consists of 7 separate polypeptides.
• The proteins act together to catalyse the formation of fatty acid from acetyl CoA and malonyl
CoA.
• The enzyme fatty acid synthase has two thiol groups : one on the ACP and the other on KS.
4. Fatty Acid Synthase
Component Abbreviation Role
Acyl Carrier Protein ACP Carries Acyl group in thioester linkage
Acyl CoA ACP Transacetylase AT Transfers acyl groups from CoA to cysteine residues of
KS
Malonyl CoA ACP Transferase MT Transfer malonyl group from CoA to ACP
β-Keto acyl ACP Synthase KS Condenses acyl and malonyl groups
β-Keto acyl ACP Reductase KR Reduces β – keto group to β – Hydroxy group
β – Hydroxy Acyl ACP
Dehydrogenase
HD Removes H2O from β – Hydroxy Acyl ACP
creating double bond
Enoyl ACP Reductase ER Reduces double bond forming saturated acyl
ACP
5. Fatty Acid Synthase
Acyl Carrier Protein ACP
Acyl CoA ACP
Transacetylase
AT
Malonyl CoA ACP
Transferase
MT
β-Keto acyl ACP
Synthase
KS
β-Keto acyl ACP
Reductase
KR
β – Hydroxy Acyl ACP
Dehydrogenase
HD
Enoyl ACP Reductase ER
6. Steps involved :
Transfer of acetyl group of acetyl CoA to -SH group of
KS (Enzyme- AT).
Transfer of malonyl group of malonyl CoA to –SH group
of ACP (Enzyme – MT).
Condensation (KS)
Reduction of carbonyl group (KR)
Dehydration (HD)
Reduction of double bond (ER)
