Malonyl-Acyl Carrier Protein

Definition

Malonyl-acyl carrier protein (malonyl-ACP) is a crucial intermediate in the biosynthesis of fatty acids, serving as the donor of the two-carbon malonyl group for the iterative elongation of the fatty acid chain. It is an essential component in the biological carbonyl condensation reactions that drive fatty acid synthesis.

5 Must Know Facts For Your Next Test

1. Malonyl-ACP is produced from malonyl-CoA by the action of the enzyme malonyl-CoA:ACP transacylase.
2. The malonyl group donated by malonyl-ACP is added to the growing fatty acid chain during each cycle of fatty acid synthesis.
3. Malonyl-ACP provides the two-carbon extender unit that allows the fatty acid chain to be elongated by two carbons in each condensation reaction.
4. The malonyl group is decarboxylated and then condensed with the growing acyl chain, catalyzed by the ketoacyl synthase domain of fatty acid synthase.
5. Malonyl-ACP is an essential substrate for the iterative, cyclic process of fatty acid chain elongation.

Review Questions

• Explain the role of malonyl-ACP in the biosynthesis of fatty acids.
  • Malonyl-ACP is a critical intermediate in the fatty acid synthesis pathway. It serves as the donor of the two-carbon malonyl group that is added to the growing fatty acid chain during each cycle of the iterative elongation process. The malonyl group is decarboxylated and then condensed with the acyl chain, catalyzed by the ketoacyl synthase domain of the fatty acid synthase complex. This allows the fatty acid chain to be extended by two carbons in each condensation reaction, ultimately leading to the formation of longer-chain fatty acids.
• Describe the relationship between malonyl-ACP and the fatty acid synthase enzyme complex.
  • Malonyl-ACP is an essential substrate for the fatty acid synthase enzyme complex, which catalyzes the stepwise synthesis of fatty acids. The malonyl group donated by malonyl-ACP is added to the growing fatty acid chain during each cycle of the condensation reactions carried out by the various domains of the fatty acid synthase complex. The malonyl-ACP intermediate is produced from malonyl-CoA by the action of the enzyme malonyl-CoA:ACP transacylase, and it is then utilized by the ketoacyl synthase domain of fatty acid synthase to extend the acyl chain by two carbons.
• Analyze the importance of the malonyl group in the context of biological carbonyl condensation reactions involved in fatty acid synthesis.
  • The malonyl group provided by malonyl-ACP is crucial for the biological carbonyl condensation reactions that drive fatty acid synthesis. The decarboxylation and subsequent condensation of the malonyl group with the growing acyl chain, catalyzed by the ketoacyl synthase domain of fatty acid synthase, allows the fatty acid chain to be elongated by two carbons in each cycle of the iterative process. This stepwise addition of the malonyl group is essential for the formation of longer-chain fatty acids, which are important structural components of cell membranes and serve as energy storage molecules. The malonyl-ACP intermediate, therefore, plays a central role in the biosynthesis of fatty acids through these key carbonyl condensation reactions.

Related terms

Acyl Carrier Protein (ACP): A small, acidic protein that covalently binds acyl groups and transports them between the different enzymatic sites involved in fatty acid synthesis.

Fatty Acid Synthase:

A multi-enzyme complex that catalyzes the stepwise synthesis of fatty acids from acetyl-CoA and malonyl-CoA precursors.

Malonate:

The dicarboxylic acid that is converted to malonyl-CoA, the substrate for the formation of malonyl-ACP.