Quick high yield concept for you today!
Concept: Competitive vs. Noncompetitive Inhibition (Concise)
At baseline:
Vmax = maximum reaction rate
Km = substrate concentration at ½ Vmax, reflects apparent affinity
Key Differences
Feature | Competitive Inhibition | Noncompetitive Inhibition (Pure) |
|---|---|---|
Binds to | Active site | Allosteric site |
Competes with substrate? | Yes | No |
Effect on Vmax | No change | Decreases |
Effect on Km | Increases | No change |
Can adding substrate fix it? | Yes | No |
Lineweaver–Burk change | Same y-intercept | Same x-intercept |
Why
Competitive: Substrate and inhibitor fight for the same site. Add more substrate and you can outcompete the inhibitor. Maximum rate is still possible, but you need more substrate to get there → Km increases.
Noncompetitive: Inhibitor reduces functional enzyme amount. Substrate cannot reverse this → Vmax drops, Km unchanged.
MCAT Shortcut:
If increasing substrate restores max rate → competitive.
If it does not → noncompetitive.
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