What enzymatic process does Fatty-acid Synthetase (FAS) facilitate?

Fatty-acid Synthetase (FAS) is a multi-enzyme complex that plays a crucial role in the biosynthesis of fatty acids. The enzymatic process facilitated by FAS involves a series of distinct reactions: condensation, reduction, dehydration, and reduction.

During fatty acid synthesis, FAS begins with the condensation reaction, where acetyl-CoA (or malonyl-CoA) is added to the growing fatty acid chain. Following this, the molecule undergoes a reduction step, facilitated by an enzyme in the FAS complex that converts a ketone group into a hydroxyl group. This is typically done using NADPH as a reducing agent.

Next, dehydration occurs, where a water molecule is eliminated, creating a double bond in the fatty acid chain. Finally, another reduction step takes place to convert the newly formed double bond into a saturated bond, making the fatty acid fully saturated.

This sequence of reactions is what gives FAS its ability to efficiently synthesize fatty acids, thereby confirming that it indeed coordinates multiple processes: condensation, reduction, dehydration, and another reduction at the end. Understanding this series of reactions is essential for grasping the overall function of fatty-acid synthase in lipid metabolism.