FATTY BIOSYNTHESIS IN PLANTS

You may have been searching the internet on How is fatty acids synthesized in plants? biocience24 is here to provide a simplified tutor on the biosynthesis of fatty acids. Are youb ready? Lets go…

Acetyl-CoA serves as the precusors/source of carbonfor the biosynthesis of of fatty acids. It enters into the “De Novo Synthesis” to yeld an acyl-ACP (acyl carrier protein). The carbon chains of the acyl-ACP is broken off when it reaches the 16 carbon ( palmitoyl) and sometimes steroyl.

lets go in details to the steps in this synthesis pathway. The first committed step converts acetyl-CoA to malonyl-CoA by the enzyme acetyl-CoA carboxylase. This reaction has two partial reaction./ The complex enzyme uses ATP ( adenosintriphosphate) and bicarbonate to carboxylate a biotin group by the enzyme biotin carboxylase. The next partial reaction transfers carboxy group to the acceptor acetyl-CoA by the catalyzing effect of the enzyme carboxy transferase to form malonyl-CoA.

Note : This is the rate limiting step of fatty acid biosynthesis. ( the convertion of acetyl-CoA to malonyl-CoA by the enzyme acetyl-CoA carboxylase)

Lets shortly look at the second step, are you ready? The next step converts the previously formed intermediate (malonyl-CoA) into malonyl-ACP. This happens through the enzyme carboxy transferase which transfers the ACP to the malonyl and discharging the previous -CoA group.

The next step involves a condensaton reaction. Malonyl-ACP is condenced with an acyl-ACP to form 3-ketoacyl-ACP and liberating CO2. The enzyme that catalyzes this reaction is called B-ketoacyl-ACP synthase.

In the next reaction, NADPHH is used to reduce 3-ketoacyl-ACP to 3-hydroxyl-ACP by the enzyme B- ketoacyl-ACP reductase.

B-hydroxyacyl-ACP dehydrase removes water molecule from the later to form enoyl-ACP.

Enoyl-ACP reductase reduces enoyl -ACP to the long R-acyl -ACP

On reaching the 16 carbon atoms, it will be cut off as fatty acid (palmitic acid).

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