Which description best captures the induced fit theory?

Which description best captures the induced fit theory?

• A. The active site is rigid
• B. The enzyme is flexible and can mould itself around the substrate when it binds
• C. The substrate molds the enzyme
• D. The enzyme and substrate fit only after the reaction

Answer: (B)

Induced fit describes a flexible enzyme active site that reshapes itself as the substrate approaches and binds. This conformational change helps bring catalytic groups into the right positions, stabilizes the transition state, and lowers the activation energy needed for the reaction. The initial contact isn’t a perfect lock-and-key; instead the enzyme molds around the substrate to achieve a snug fit that enables catalysis. The idea that the active site is rigid contradicts this flexibility, and the notion that the substrate alone molds the enzyme overstates its role. The fit occurs during binding, enabling catalysis, not only after the reaction has started.

Induced fit describes a flexible enzyme active site that reshapes itself as the substrate approaches and binds. This conformational change helps bring catalytic groups into the right positions, stabilizes the transition state, and lowers the activation energy needed for the reaction. The initial contact isn’t a perfect lock-and-key; instead the enzyme molds around the substrate to achieve a snug fit that enables catalysis. The idea that the active site is rigid contradicts this flexibility, and the notion that the substrate alone molds the enzyme overstates its role. The fit occurs during binding, enabling catalysis, not only after the reaction has started.