Substrates fit rigid sites in one model and the enzyme reshapes on binding in the other.
Practise Biochemistry, Environment & Industry All Biochemistry, Environment & Industry topics
The lock and key model, proposed by Emil Fischer in 1894, pictures the enzyme active site as a rigid template that matches only one substrate shape. The induced fit model, proposed by Koshland in 1958, says the enzyme and substrate both change shape during binding, bringing catalytic groups into the correct position. Induced fit explains why many enzymes accept a range of related substrates and why the transition state is stabilised more than the ground state. Both models agree that binding is specific, and modern structural studies favour induced fit as the better description for most enzymes. Understanding conformational change helps in designing inhibitors that trap an enzyme in an inactive shape.
Key ideas: Fischer lock and key (1894) proposes a rigid, pre-shaped active site. Koshland induced fit (1958) says binding changes the enzyme shape so the site wraps around the substrate and strains bonds toward the transition state. Induced fit explains why enzymes accept some related substrates and how conformational change helps catalysis.
Common mistakes and connections: Students treat the lock and key model as wrong; it is a simplification that works for some enzymes. Another error is thinking induced fit means low specificity; the change is what ensures correct alignment of catalytic groups. Links to allosteric regulation and drug binding to receptors.
Binding energy versus separation has a well where attraction and repulsion balance. A good fit between enzyme and substrate sits at the minimum, as in induced fit binding. The interactive lesson shows this as a live animation or chart.
Hexokinase undergoes a large closing motion around glucose, which excludes water from the active site.
Substrates fit rigid sites in one model and the enzyme reshapes on binding in the other.
Lock and Key vs Induced Fit is a intermediate topic in Biochemistry, Environment & Industry. It builds on the vocabulary of beginner topics in this area.
Study these earlier topics in Biochemistry, Environment & Industry first: Essential Amino Acids, Enzymes, Active Site.
The next topics in Biochemistry, Environment & Industry are Cofactors and Coenzymes and Vitamins.
Yes. The interactive lesson includes a self-check question on Lock and Key vs Induced Fit, and the Biochemistry, Environment & Industry quiz draws on every topic in this area.
Lock and Key vs Induced Fit is topic 14 of 127 in Biochemistry, Environment & Industry.
Browse all 127 topics in Biochemistry, Environment & Industry