Lock and key model Induced and fit model
Chapter Enzymes | Lock & Key Model – Induced Fit Model
What Are Enzymes?
Enzymes are protein catalysts that speed up biochemical reactions by lowering the activation energy, while remaining unchanged themselves.
Lock & Key Model
Concept: The enzyme’s active site is a rigid, precisely shaped pocket into which only the matching substrate fits—like a key into a lock.
- Substrate Specificity: High specificity due to complementary shapes.
- Limitations: Does not account for flexibility or conformational changes.
Induced Fit Model
Concept: The enzyme’s active site is flexible and molds itself around the substrate upon binding, creating a more precise fit.
- Dynamic Interaction: Conformational change stabilizes the transition state.
- Enhanced Catalysis: Adjustments in shape optimize interactions and lower activation energy further.
Comparison of Models
| Feature | Lock & Key | Induced Fit |
|---|---|---|
| Active Site Shape | Rigid | Flexible |
| Substrate Binding | Exact complementarity | Conformational adjustment |
| Transition State Stabilization | Limited | Enhanced |
| Model Origin | Emil Fischer, 1894 | Daniel Koshland, 1958 |
Biological Significance
Understanding these models helps explain enzyme specificity, regulation, and mechanisms of inhibitors—critical for drug design and biotechnology applications.
