Biology
Explainer
Competitive vs Non-competitive Inhibition
Two inhibitors can slow an enzyme equally yet change Km and Vmax differently.
Quick check · tap an answer to continue
Lesson notes
Key points
- In Michaelis–Menten kinetics, Vmax is the maximum rate and Km is the substrate concentration giving half of Vmax.
- A competitive inhibitor binds the active site, so extra substrate outcompetes it: apparent Km rises while Vmax stays unchanged.
- A pure non-competitive inhibitor binds elsewhere, reducing working enzyme, so Vmax falls while Km stays the same.
Definitions
- Competitive inhibitor
- Binds the active site, competing with substrate; overcome by high [S]; raises apparent Km, Vmax unchanged
Takeaway: Competitive raises Km; non-competitive lowers Vmax.
Quick check: Adding lots of substrate restores Vmax. Which inhibitor?
- Non-competitive
- Uncompetitive
- Competitive
Michaelis–MentenCompetitiveNon-competitive
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