Feedback inhibition
- Feedback inhibition is also known as end-product inhibition.
- It is a regulatory mechanism in which the final product of a metabolic pathway inhibits the activity of an enzyme or enzymes earlier in the pathway.
- This mechanism helps maintain homeostasis, control the rate of biochemical reactions, and prevent the excessive accumulation of end products.
Regulation of feedback inhibition
The regulation of feedback inhibition involves several key steps:
- Initial Enzymatic Reactions:
- A series of enzymatic reactions occur in a metabolic pathway, with each reaction catalyzed by a specific enzyme.
- These reactions convert substrates into intermediate products, which are further processed to produce the final end product.
- Accumulation of End Product:
- As the metabolic pathway progresses, the concentration of the end product increases.
- This increase can be due to various factors, such as substrate availability, enzyme activity, and cellular demand.
- Binding of End Product:
- The end product binds to a specific site, called the allosteric site, on the regulatory enzyme involved in the first step of the pathway.
- This binding induces a conformational change in the enzyme, altering its activity.
- Inhibition of Enzyme Activity:
- The conformational change caused by the binding of the end product inhibits the enzyme’s activity.
- This inhibition can occur through different mechanisms, such as blocking the active site, modifying the enzyme’s affinity for substrates, or interfering with the enzyme-substrate complex formation.
- Down regulation of Pathway:
- By inhibiting the activity of the regulatory enzyme, feedback inhibition slows down or halts the entire metabolic pathway.
- This down regulation prevents the overproduction of the end product and conserves cellular resources.
- Restoration of Equilibrium:
- As the concentration of the end product decreases, it is no longer bound to the allosteric site of the regulatory enzyme.
- This relieves the inhibition and allows the pathway to resume its activity, producing more end products when needed.
Role of feedback inhibition:
- Feedback inhibition is vital for maintaining metabolic balance and preventing the accumulation of excess end products.
- It helps regulate the flow of metabolites, optimizing their production according to the cellular needs.
- By sensing and responding to changes in end product levels, feedback inhibition ensures that the metabolic pathways are controlled and efficient.
| Aspect | Description |
| Definition | · Feedback inhibition, also known as end-product inhibition
· It is a regulatory mechanism in which the final product of a metabolic pathway inhibits the activity of an enzyme or enzymes earlier in the pathway. |
| Purpose | · Maintains homeostasis · Controls the rate of biochemical reactions · Prevents the excessive accumulation of end products |
| Regulatory Step | · The end product of a metabolic pathway binds to the allosteric site of the regulatory enzyme involved in the first step of the pathway. |
| Mechanism | · Binding of the end product induces a conformational change in the regulatory enzyme, inhibiting its activity.
· This can occur by blocking the active site, altering substrate affinity, or interfering with the enzyme-substrate complex formation. |
| Down regulation | · Inhibition of the regulatory enzyme slows down or halts the entire metabolic pathway
· Preventing the overproduction of end products |
| Restoration | · As the concentration of the end product decreases, it dissociates from the allosteric site.
· Relieving the inhibition and allowing the pathway to resume its activity when needed. |
| Significance | · Maintains metabolic balance
· Prevents wasteful or harmful accumulation of end products · Optimizes production according to cellular needs |
| Examples | · Citric acid cycle
· Fatty acid synthesis · Amino acid biosynthesis · Cholesterol synthesis. |
| Biological Impact
|
· Essential for cellular homeostasis
· Energy conservation, and · Efficient resource utilization. · Plays a crucial role in regulating metabolic activities and ensuring the stability and functionality of biological systems. |