Ans: B.)Non-competitive inhibition
In the graph shown in the image, Y-axis shows the Velocity(rate of reaction), X-axis shows the substrate concentration, “A’-shows normal enzyme, “B” shows competitive inhibition and “C” shows non-competitive inhibition.
- This maximum rate of reaction is characteristic of a particular enzyme at a particular concentration and is known as the maximum velocity or Vmax.
- The substrate concentration that gives you a rate that is halfway to Vmax is called Km.
- Competitive inhibitors:
- They impair reaction progress by binding to an enzyme, often at the active site, and preventing the real substrate from binding.
- At any given time, only the competitive inhibitor or the substrate can be bound to the enzyme (not both).
- Competitive inhibition acts by decreasing the number of enzyme molecules available to bind the substrate.
- With a competitive inhibitor, the reaction can eventually reach its normal Vmax
- but it takes a higher concentration of the substrate to get it there. Vmax is unchanged but Km is higher
- Noncompetitive inhibitors:
- They don’t prevent the substrate from binding to the enzyme.
- In fact, the inhibitor and substrate don’t affect one another’s binding to the enzyme at all.
- However, when the inhibitor is bound, the enzyme cannot catalyze its reaction to produce a product.
- Thus, noncompetitive inhibition acts by reducing the number of functional enzyme molecules that can carry out a reaction.
- With a noncompetitive inhibitor, the reaction can never reach its normal Vmax regardless of how much substrate we add. Km is unchanged.