Fatty acid synthase

Definition

Fatty acid synthase is a multi-enzyme complex that catalyzes the biosynthesis of fatty acids from acetyl-CoA and malonyl-CoA through a series of reactions involving reduction, dehydration, and condensation. This enzyme plays a critical role in lipid metabolism and energy storage, facilitating the conversion of carbohydrates into fats in organisms.

5 Must Know Facts For Your Next Test

1. Fatty acid synthase operates as a dimer, meaning two identical enzyme units work together to synthesize fatty acids efficiently.
2. The process of fatty acid synthesis involves multiple cycles, each adding two carbon atoms to the growing fatty acid chain until it reaches its final length, typically 16 or 18 carbons.
3. NADPH is crucial for fatty acid synthase activity, providing the reducing power needed for the reduction steps during fatty acid synthesis.
4. Regulation of fatty acid synthase is influenced by various factors such as insulin levels and nutrient availability, linking it to overall energy homeostasis in the body.
5. Fatty acid synthase primarily produces palmitate, which can be further elongated or desaturated to create other types of fatty acids necessary for cellular functions.

Review Questions

• How does fatty acid synthase function in the context of lipid metabolism?
  • Fatty acid synthase functions as a key player in lipid metabolism by converting simple precursors like acetyl-CoA and malonyl-CoA into long-chain fatty acids. It uses a series of enzymatic reactions that involve both condensation and reduction processes. By synthesizing fatty acids, it facilitates the storage of energy in the form of triglycerides, which can be utilized later when needed. This process connects carbohydrate metabolism with fat storage, highlighting its importance in maintaining energy balance.
• What is the role of NADPH in the activity of fatty acid synthase, and why is it important?
  • NADPH acts as a reducing agent in the reactions catalyzed by fatty acid synthase, specifically during the reduction steps where double bonds are saturated. It provides the necessary electrons for these reductions to occur, allowing the conversion of carbon chains into saturated fatty acids. The availability of NADPH is crucial because it directly influences the rate of fatty acid synthesis. If NADPH levels are low, the synthesis process can slow down or be impaired, affecting lipid metabolism and energy storage.
• Evaluate how changes in insulin levels affect the regulation of fatty acid synthase and its implications on overall metabolism.
  • Insulin plays a significant role in regulating fatty acid synthase activity by promoting its expression and enhancing its enzymatic function. When insulin levels rise, typically after carbohydrate-rich meals, fatty acid synthase becomes more active, leading to increased lipogenesis or fat storage. Conversely, low insulin levels can inhibit this enzyme's activity, shifting metabolism towards fat utilization rather than storage. This regulatory mechanism illustrates how hormonal control affects metabolic pathways and energy homeostasis within the body.

Related terms

Acetyl-CoA: A central metabolic intermediate derived from carbohydrates, fats, and proteins that serves as a building block for fatty acid synthesis.

Malonyl-CoA: A three-carbon molecule that provides the carbon units for fatty acid elongation during the synthesis process.

Lipid Metabolism: The biochemical processes involved in the synthesis and degradation of lipids, including fatty acids, which are essential for cellular structure and energy storage.