Fatty acid synthase

Definition

Fatty acid synthase is a multi-enzyme complex responsible for the synthesis of fatty acids from acetyl-CoA and malonyl-CoA through a series of condensation, reduction, dehydration, and another reduction reactions. This enzyme plays a crucial role in lipid metabolism, facilitating the conversion of carbohydrates and proteins into fatty acids that can be stored as triglycerides or used for energy production.

5 Must Know Facts For Your Next Test

1. Fatty acid synthase operates in the cytosol of cells and is particularly abundant in liver and adipose tissue, where fatty acid synthesis primarily occurs.
2. The process of fatty acid synthesis involves the addition of two-carbon units, leading to the production of long-chain fatty acids typically ending with palmitate (C16:0).
3. Fatty acid synthase functions as a dimer, with each monomer containing multiple enzymatic domains that work together to catalyze different steps of the synthesis process.
4. Regulation of fatty acid synthase activity is influenced by hormonal signals such as insulin, which promotes fatty acid synthesis, while glucagon has an opposing effect.
5. Malonyl-CoA not only serves as a substrate for fatty acid synthase but also inhibits carnitine acyltransferase I, preventing fatty acid oxidation when fatty acid synthesis is active.

Review Questions

• How does fatty acid synthase contribute to lipid metabolism and what are its primary substrates?
  • Fatty acid synthase is essential in lipid metabolism as it catalyzes the formation of fatty acids from its primary substrates, acetyl-CoA and malonyl-CoA. Acetyl-CoA provides the initial two-carbon unit for synthesis, while malonyl-CoA donates additional two-carbon units through a series of enzymatic reactions. This process is vital for converting excess carbohydrates and proteins into stored fats, influencing energy balance and fat storage in the body.
• Discuss how hormonal regulation affects the activity of fatty acid synthase in relation to metabolic states.
  • Hormonal regulation plays a significant role in modulating the activity of fatty acid synthase. For instance, insulin promotes fatty acid synthesis by enhancing the expression and activity of this enzyme when energy substrates are abundant. Conversely, during fasting or low-energy states, glucagon and epinephrine signal for a reduction in fatty acid synthase activity, shifting metabolism towards fat oxidation instead. This balance ensures that energy production aligns with the body's needs under varying nutritional conditions.
• Evaluate the implications of altered fatty acid synthase activity on human health and metabolic disorders.
  • Altered activity of fatty acid synthase has significant implications for human health, particularly in metabolic disorders such as obesity and diabetes. Increased expression or activity can lead to excessive fatty acid synthesis, contributing to triglyceride accumulation and obesity-related complications. Conversely, reduced activity may impair lipid metabolism and energy storage. Understanding these dynamics allows researchers to explore therapeutic targets for regulating fatty acid synthase in managing metabolic diseases effectively.

Related terms

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

Malonyl-CoA: A three-carbon molecule that acts as a substrate for fatty acid synthase, providing the carbon units required for the elongation of fatty acids during synthesis.

Triglycerides: The main form of stored fat in the body, formed from glycerol and three fatty acid molecules; they serve as an important energy reserve.