Fatty acid synthesis


Fatty acid synthesis

Fatty acids are formed by the action of Fatty acid synthases from acetyl-CoA and malonyl-CoA precursors.

De Novo Synthesis in Humans

In humans fatty acids are predominantly formed in the liver and adipose tissue, and mammary glands during lactation. Most acetyl-CoA is formed from pyruvate by pyruvate dehydrogenase in the mitochondria. Acetyl-CoA produced in the mitochondria is condensed with oxaloacetate to form citrate, which is then transported into the cytosol and broken down to yield acetyl-CoA and oxaloacetate by ATP citrate lyase.

Elongation

Much like β-oxidation, elongation occurs via four recurring reactions shown below. In these diagrams, the acetyl and malonyl units are shown as their Acyl carrier protein thioesters: this is how fatty acids are synthesized in microorganisms and plants. However, in animals these same reactions occur on a large dimeric protein, Fatty acid synthase, which has the full complement of enzymatic activities required to synthesize and liberate a free fatty acid.

In the second step of elongation, butyryl ACP condenses with malonyl ACP to form an acyl ACP compound. This continues until a C16 acyl compound is formed, at which point it is hydrolyzed by a "thioesterase" into palmitate and ACP.

External links

* [http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb2/part1/fasynthesis.htm Overview] at Rensselaer Polytechnic Institute
* [http://web.indstate.edu/thcme/mwking/lipid-synthesis.html#synthesis Overview] at Indiana State University


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