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What are the differences between induced fit & lock and key model?
Posted February 3, 2023
Cellular ProcessesEnzymes
Answer
The induced fit and lock-and-key model are two proposed models that explain how substrates may bind to the active site of an enzyme. There are several significant differences between the two models. 

Induced Fit Model

  • Refers to an enzyme-substrate interaction model in which the active site of the enzyme does not fit the substrate completely
  • Shapes are not complementary before binding
  • The active site of the enzyme contains two components 
  • The active site of the enzyme is not static and has to undergo a conformational change to improve binding
  • Binding is flexible and not very strong
  • A transition state develops before the reactants undergo changes
  • The enzyme has a separate catalytic group, which weakens the substrate bonds either by the nucleophilic or electrophilic attack 
  • Proposed by Daniel Koshland in 1958

Lock & Key Model

  • Refers to an enzyme-substrate interaction model in which the active site of the enzyme precisely fits with the substrate 
  • Shapes are complementary with each other before binding
  • The active site of the enzyme contains a single entity 
  • The active site of the enzyme is static and does not undergo any conformational changes before binding
  • Binding is inflexible and very strong
  • A transition state does not develop before the reactants undergo changes
  • The enzyme does not have a separate catalytic group hence there is no weakening of the substrate bonds 
  • Proposed by Emil Fischer in 1894
Additional resources
"Lock and Key" and "Induced-Fit" Host-Guest Models in Two Digold(I)-Based Metallotweezers EnzymesAc-DEVD-AFC *CAS 201608-14-2* Amplite® Fluorimetric Acetylcholinesterase Assay Kit *Red Fluorescence*

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