In this analogy, the lock is the enzyme and the key is the substrate. Only the correctly sized key (substrate) fits into the key hole (active site) of the lock (enzyme).

How does lock and key theory work?

Lock and key hypothesis

Enzymes are folded into complex 3D shapes that allow smaller molecules to fit into them. The place where these molecules fit is called the active site . In the lock and key hypothesis , the shape of the active site matches the shape of its substrate molecules. This makes enzymes highly specific.

What is the difference between the lock and key and induced fit models?

The main difference between induced fit and lock and key model is that in the induced fit model, the active site of the enzyme does not completely fit to the substrate whereas in the lock and key model, the active site of the enzyme is the complement of the substrate and hence, it precisely fits to the substrate.

Why lock and key hypothesis is wrong?

The lock and key model is not entirely wrong, just simplified. The original model suggested the existence of an enzyme in a rigid conformation where the active site is complementary to the substrate. The enzyme must have conformational flexibility to catalyze reactions in this way.

What are the weaknesses of lock and key model?

The lock and key model for enzyme activity is wrong because it does not account for the intermediate shape of the substrate. In reality, if the situation really was “lock-and-key,” the substrate would get stuck in the enzyme and be unable to move or be released.

Is the lock and key model accurate?

Like a key into a lock, only the correct size and shape of the substrate (the key) would fit into the active site (the keyhole) of the enzyme (the lock). It shows the high specificity of enzymes. However, it does not explain the stabilization of the transition state that the enzymes achieve.