Differentiate between competitive and non competitive inhibition of enzymes.
The correct answer and explanation is:
Competitive Inhibition:
In competitive inhibition, the inhibitor molecule is structurally similar to the substrate. It competes with the substrate for binding to the active site of the enzyme. When the inhibitor binds to the active site, it prevents the substrate from attaching, thereby reducing the rate of the enzyme-catalyzed reaction. However, the inhibition is reversible, and the effect can be overcome by increasing the substrate concentration. This is because the likelihood of the substrate binding to the enzyme increases as more substrate is available.
Non-Competitive Inhibition:
In non-competitive inhibition, the inhibitor binds to a different site on the enzyme, known as the allosteric site, rather than the active site. This binding causes a conformational change in the enzyme’s structure, which affects the enzyme’s ability to catalyze the reaction. The inhibitor does not compete with the substrate for the active site. The binding of the inhibitor reduces the enzyme’s efficiency, even if the substrate is bound. This type of inhibition cannot be reversed by increasing the substrate concentration because the enzyme’s ability to function is altered due to the conformational change.
Key Differences:
- Binding Site: In competitive inhibition, the inhibitor and substrate both bind to the active site of the enzyme. In non-competitive inhibition, the inhibitor binds to an allosteric site, not the active site.
- Effect of Substrate Concentration: In competitive inhibition, increasing the substrate concentration can overcome the inhibition. In non-competitive inhibition, increasing the substrate concentration does not affect the inhibition.
- Mechanism: Competitive inhibition simply blocks the active site, while non-competitive inhibition alters the enzyme’s shape, impacting its function.
In summary, competitive inhibition reduces the enzyme’s activity by blocking the active site, while non-competitive inhibition alters the enzyme’s structure, preventing proper catalysis.