What does the lock and key hypothesis explain?

The lock and key hypothesis describes how substrates fit precisely into the active site of enzymes, much like a key fits into a lock. This analogy emphasizes the specificity of enzyme-substrate interactions. According to this hypothesis, the enzyme's active site has a specific shape that is complementary to the shape of its target substrate, allowing for efficient binding.

When the substrate binds to the active site, it forms an enzyme-substrate complex, which facilitates the biochemical reaction. This specificity is crucial because it ensures that enzymes catalyze only specific reactions, maintaining the efficiency and regulation of metabolic processes within the cell.

The other concepts mentioned do not directly relate to how substrates interact with enzymes in a specific manner. For example, energy levels of reactants pertain more to thermodynamics than to the interaction mechanism between enzymes and substrates. Similarly, enzyme stability under extreme conditions and shape changes after binding involve broader aspects of enzyme behavior and function, but they do not directly convey the precise matching process highlighted by the lock and key hypothesis.