Enzyme inhibitors are substances that slow down or stop enzyme activity.
There are two main types — competitive and non-competitive inhibitors.
1. Competitive inhibitors
- They look like the substrate and try to fit into the active site of the enzyme.
- Because they block the active site, the real substrate cannot bind.
- If you add more substrate, it can push the inhibitor out, and the enzyme can work again.
Example:
Malonic acid blocks the enzyme that normally works with succinate.
2. Non-competitive inhibitors
- They bind to a different place on the enzyme, not the active site.
- This changes the enzyme’s shape, so the active site no longer fits the substrate.
- Adding more substrate does not help, because the enzyme’s shape is already changed.
Example:
Cyanide stops the enzyme needed for energy production in cells.
In short:
- Competitive inhibitor: Blocks the active site.
- Non-competitive inhibitor: Changes the enzyme’s shape.