Give suitable examples to explain the induced fit hypothesis of enzyme action

If you are looking for an analogy, the induced fit model is like a carpenter nailing boards together. The carpenter must first arrange the boards in the proper orientation, then fasten them together by hammering in nails. In this example, the carpenter and his hands represent the enzyme, while the boards represent the substrate and the nails represent ions attached to the enzyme that do the actual making of chemical bonds between substrate segments.

Conversely, a carpenter may reverse the process, using a nail puller to remove nails that connect two boards. In this example, the carpenter and his hands represent the enzyme, while the nailed boards represent the substrate and the nail puller represents ions attached to the enzyme that do the actual breaking of chemical bonds in the substrate.

Enzymes are specific to reactants(known as substrates). That is, enzymes only catalyse one type of reaction.

The lock and key model helps us understand this concept. The enzyme is like a lock, and the substrate is like a key. Only specific substrate works with an enzyme, just like a specific key is required for a lock. The lock represents the active site on the enzyme, where the substrate binds.

In recent research however, the lock and key model is disputed, with the induced fit being more likely. The induced fit model says that when an substrate binds to an enzyme, the enzyme temporarily changes shape to accommodate the substrate. While the enzyme is still specific to substrates, it is not as if the substrate is a perfect fit on the active site of the enzyme. After the reaction is complete, the enzyme returns back to its original shape, ready to be reused.

While the induced fit model is more likely to be correct from current evidence, the lock and key model is still used because it allows a simple diagrammatic way to understand the specificity of enzymes.