key term - $\beta$-ketoacyl ACP synthase

Definition

$\beta$-ketoacyl ACP synthase is a critical enzyme involved in the biosynthesis of fatty acids. It catalyzes the addition of a two-carbon unit to the growing fatty acid chain, a key step in the iterative process of fatty acid elongation.

5 Must Know Facts For Your Next Test

1. $\beta$-ketoacyl ACP synthase is also known as fatty acid synthase (FAS) or 3-ketoacyl-ACP synthase.
2. It catalyzes the condensation reaction between malonyl-ACP and the growing acyl-ACP chain, adding a two-carbon unit to the chain.
3. This enzyme is part of the fatty acid synthase complex, which is responsible for the de novo synthesis of palmitic acid (16:0) from acetyl-CoA and malonyl-CoA.
4. The $\beta$-ketoacyl ACP synthase reaction is repeated iteratively to elongate the fatty acid chain by two carbons with each cycle.
5. Regulation of $\beta$-ketoacyl ACP synthase activity is crucial for controlling the rate of fatty acid biosynthesis and maintaining cellular lipid homeostasis.

Review Questions

• Describe the role of $\beta$-ketoacyl ACP synthase in the biosynthesis of fatty acids.
  • $\beta$-ketoacyl ACP synthase is a key enzyme in the fatty acid biosynthesis pathway. It catalyzes the condensation reaction between malonyl-ACP and the growing acyl-ACP chain, adding a two-carbon unit to the chain. This iterative process is repeated to elongate the fatty acid to the desired length, typically resulting in the synthesis of palmitic acid (16:0). The regulation of $\beta$-ketoacyl ACP synthase activity is crucial for controlling the rate of fatty acid biosynthesis and maintaining cellular lipid homeostasis.
• Explain how $\beta$-ketoacyl ACP synthase is integrated into the overall fatty acid biosynthesis pathway.
  • $\beta$-ketoacyl ACP synthase is a central component of the fatty acid synthase complex, which is responsible for the de novo synthesis of palmitic acid from acetyl-CoA and malonyl-CoA. The $\beta$-ketoacyl ACP synthase reaction, which adds a two-carbon unit to the growing fatty acid chain, is repeated iteratively to elongate the chain. This enzyme works in coordination with other enzymes, such as acetyl-CoA carboxylase and acyl carrier protein (ACP), to facilitate the step-by-step construction of fatty acids. The regulation of $\beta$-ketoacyl ACP synthase activity is crucial for controlling the overall rate and product distribution of the fatty acid biosynthesis pathway.
• Analyze the significance of $\beta$-ketoacyl ACP synthase in the context of cellular lipid metabolism and homeostasis.
  • $\beta$-ketoacyl ACP synthase plays a pivotal role in cellular lipid metabolism and homeostasis. As the key enzyme responsible for the iterative elongation of fatty acid chains, $\beta$-ketoacyl ACP synthase activity directly determines the availability of fatty acids for the synthesis of various lipid molecules, such as phospholipids, triglycerides, and lipid-based signaling molecules. The regulation of $\beta$-ketoacyl ACP synthase, influenced by factors like nutrient availability and hormonal signals, allows the cell to fine-tune its fatty acid biosynthesis and maintain the appropriate balance of lipids required for membrane structure, energy storage, and signaling functions. Dysregulation of $\beta$-ketoacyl ACP synthase can lead to imbalances in cellular lipid homeostasis, contributing to various metabolic disorders and disease states.

Related terms

Fatty Acid Biosynthesis:

The metabolic pathway responsible for the synthesis of fatty acids, which are essential components of cell membranes and energy storage molecules.

Acetyl-CoA Carboxylase: The enzyme that catalyzes the first committed step in fatty acid biosynthesis, converting acetyl-CoA to malonyl-CoA, the two-carbon building block for fatty acid elongation.

Acyl Carrier Protein (ACP): A small, acidic protein that carries the growing fatty acid chain and shuttles it between the various enzymes involved in fatty acid biosynthesis.