Fatty Acid Biosynthesis

Vocabulary terms and definitions related to the biochemistry of fatty acid biosynthesis, including key enzymes, cofactors, and metabolic steps.

Triacylglycerols

The primary long-term energy reserve of the body where fatty acids are stored; they are highly reduced and store more energy per gram than carbohydrates.

Phospholipids

Molecules that form the structural basis of all biological membranes, utilizing fatty acids to maintain cellular compartmentalisation.

Catabolism (Oxidation)

The metabolic process that breaks down fatty acids to release energy, producing $NADH$ and $FADH_2$.

Anabolism (Synthesis)

The metabolic process that builds fatty acids, requiring energy input in the form of $ATP$ and $NADPH$.

Palmitate (C16:0)

A $16$-carbon saturated fatty acid that is the primary product of fatty acid synthesis in mammalian systems and the starting point for longer or unsaturated fatty acids.

Malonyl-CoA

The $2$-carbon donor unit used for chain elongation in fatty acid synthesis, formed by the carboxylation of acetyl-CoA.

Acetyl-CoA Carboxylase (ACC)

The enzyme that catalyzes the irreversible, rate-limiting first step of fatty acid synthesis: the formation of malonyl-CoA from acetyl-CoA.

Biotin

An essential cofactor for acetyl-CoA carboxylase that acts as a $CO_2$ carrier, temporarily holding the carboxyl group before transfer.

Fatty Acid Synthase (FAS)

A large multifunctional multi-enzyme complex located in the cytosol that catalyzes the sequential addition of $2$-carbon units to a growing fatty acid chain.

Acyl Carrier Protein (ACP)

A domain within the fatty acid synthase complex to which the growing fatty acid chain is attached during synthesis.

Condensation

The first reaction in the elongation cycle, catalyzed by $\beta$-ketoacyl-ACP synthase, which joins the acetyl and malonyl groups and releases $CO_2$.

Palmitoyl thioesterase

The enzyme responsible for the final step of synthesis, which cleaves the finished $16$-carbon palmitate from the ACP to release the free fatty acid.

Pentose Phosphate Pathway

One of the two primary metabolic routes (along with the malic enzyme) that supplies the $NADPH$ required for fatty acid synthesis.

4' phosphopantetheine

The flexible arm required by Fatty Acid Synthase to carry and move intermediates between the different active sites of the complex.

$\beta$-hydroxyacyl-ACP dehydrase

The enzyme that catalyzes the dehydration step (step $5$) of the elongation cycle, removing water to form a double bond ($\alpha\beta$ trans enoyl-ACP).