Question

question
an active field of research in computational chemistry is predicting the shapes of proteins and other large biomolecules, and understanding how their shapes affect their chemistry. suppose a chemist was trying to model the effects of a genetic mutation on the functionality of an enzyme by comparing the shapes of the healthy and mutated enzyme to the shape of the substrate. explain how the induced fit model might differ from the lock - and - key model in this study.
select the correct answer below:
according to the lock - and - key model, the chemist would only have to consider the secondary structure of the enzyme (the alpha helices and the beta sheets), but according to the induced fit model, the tertiary and quaternary structures (overall three - dimensional shape and composition of multiple subunits) are also important to understanding the function of the enzyme.
according to the lock - and - key model, the chemist would only have to compare the shapes of the isolated substrate and enzymes, but according to the induced fit model, the chemist would also have to consider the shapes of the products because the enzyme can also catalyze the reverse reaction.
according to the lock - and - key model, the shapes of the isolated substrate and enzymes could be compared directly, but according to the induced fit model, the chemist would also have to consider the conformations of the enzymes when bound to the substrate to compare the effectiveness of the enzymes.
according to the lock - and - key model, the chemist would only have to compare the shapes of the healthy and mutated enzyme to each other. according to the induced fit model, the chemist would have to compare both to the shape of the substrate.

Explanation:

• Lock - and - key model: Assumes a rigid, complementary fit between enzyme (lock) and substrate (key). Shapes of isolated enzyme and substrate are directly compared.
• Induced fit model: Enzyme changes shape (conformation) upon substrate binding. So, need to consider enzyme - substrate complex conformation (not just isolated shapes) to assess enzyme effectiveness.
• Option A: Both models consider protein structures (not just secondary vs tertiary/quaternary as stated).
• Option B: Reverse reaction (product shape) is not the main difference between lock - and - key and induced fit models in terms of shape comparison for enzyme - substrate interaction.
• Option D: Both models compare enzyme (healthy/mutated) to substrate (not just lock - and - key comparing enzyme to enzyme).

Answer:

C. According to the lock - and - key model, the shapes of the isolated substrate and enzymes could be compared directly, but according to the induced fit model, the chemist would also have to consider the conformations of the enzymes when bound to the substrate to compare the effectiveness of the enzymes.