Which model posits that both the drug and receptor may change shape for an ideal fit?

Which model posits that both the drug and receptor may change shape for an ideal fit?

• A. Lock and Key model and induced fit model
• B. Induced fit model
• C. Lock and Key model
• D. Allosteric model

Answer: (B)

This question tests understanding that binding is often an adaptive process where both partners adjust to achieve optimal fit. In the induced fit view, the receptor’s binding site is flexible and can bend or shift when the drug approaches, and the drug itself can tweak its own shape to maximize favorable contacts like hydrogen bonds, ionic interactions, and hydrophobic contacts. This mutual shaping lowers the overall energy of the bound state and explains why ligands can bind effectively even if their initial shapes aren’t a perfect match. The other models don’t describe this mutual adaptation. The lock-and-key model assumes a rigid, pre-formed fit with no structural changes in either molecule. The allosteric model involves binding at a site separate from the active site to modulate receptor activity, causing conformational changes that affect function rather than describing both partners reshaping for an ideal fit.

This question tests understanding that binding is often an adaptive process where both partners adjust to achieve optimal fit. In the induced fit view, the receptor’s binding site is flexible and can bend or shift when the drug approaches, and the drug itself can tweak its own shape to maximize favorable contacts like hydrogen bonds, ionic interactions, and hydrophobic contacts. This mutual shaping lowers the overall energy of the bound state and explains why ligands can bind effectively even if their initial shapes aren’t a perfect match.

The other models don’t describe this mutual adaptation. The lock-and-key model assumes a rigid, pre-formed fit with no structural changes in either molecule. The allosteric model involves binding at a site separate from the active site to modulate receptor activity, causing conformational changes that affect function rather than describing both partners reshaping for an ideal fit.