BRAINCAKELock and Key Hypothesis
The lock and key hypothesis was proposed by Emil Fischer in 1894 to explain how enzymes work and why they are specific.
In this model:
• the active site has a fixed, rigid shape
• only a substrate with a shape exactly complementary to the active site can fit into it, just as only the right key fits a lock
• when the substrate fits, an enzyme-substrate complex forms
• the reaction happens and an enzyme-product complex forms
• the products no longer fit, so they are released, leaving the enzyme unchanged and free to bind another substrate
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Key terms in this lesson
- active site
- The region of an enzyme, with a shape complementary to its substrate, where the substrate molecule binds and the reaction is catalysed.
- enzyme-substrate complex
- A temporary structure formed when a substrate molecule binds to the active site of an enzyme.
More in Enzymes
- Enzymes
- Extra-Cellular and Intracellular Enzymes
- Biological Catalysts
- Induced Fit Hypothesis
- Measuring Rate of Reaction
- Effect of Substrate Concentration
- Effect of Temperature
- Effect of pH
All 14 lessons in Enzymes · All Edexcel AS-level Biology topics