Fatty Acid Research Paper

A fatty acid contains a long hydrocarbon chain and a carboxylate group. Fatty acid synthesis is a process which only takes place in the cytoplasm of the cell and it consists in producing fatty acids from acetyl-CoA and NADPH. This process requires great amounts of acetyl-CoA, and most of it that is used is formed in mitochondria. The intra-mitochondrial acetyl-CoA initially reacts to form citrate, as the inner mitochondria membrane is impermeable to this compound. Tricarboxylate transport system is used to pump out the citrate out from the inner membrane which will then be cleaved in the cytosol by citrate lyase, in order to regenerate acetyl-CoA. When acetyl groups are transferred to the cytosol, oxaloacetate is formed and needs to be

Then, the malonyl group is first attached to ACP. In the condensation step, the entire butyryl group is exchanged for the carboxyl group on the malonyl residue. For acyl-S-enzyme to be from the 3-ketoacyl group will be reduced, dehydrated and, then reduced again. A new malonyl-CoA molecule combines with the –SH of 4’-phosphopantetheine, displacing the saturated acyl residues onto the free cysteine –SH group. This sequence of reactions is repeated until Palmytyl, a saturated 16-carbon acyl radical is formed. For this radical to be liberated from the enzyme complex, the activity of an enzyme called Thioesterase (deackysase) is needed. Seven cycles of condensation and reduction produce the 16-carbon saturate palmitoyl group that is still bound to ACP. (Figure 3) In general, after this point chain elongation stops and free palmitate is released from the ACP molecule by the activity in the synthase complex. It is important to state the Palmitate is the starting point for other fatty acid. Similar reactions are used to generate the modified chains and head groups of the lipid classes
In conclusion, the synthesis of palmitate from acetyl-CoA could be summarize in two parts.
The first one consists in the formation on seven malonyl-CoA molecules:
7acetyl-CoA + 7CO2 + 7ATP -> 7 malonyl-CoA + 7 ADP + 7Pi
The second part represents the seven cycles of condensation and reduction:
Acetyl-CoA + 7 malonyl-CoA + 14NADPH + 14H+ -> Palmitate + 7CO2 + 8CoA + 14NADP+