Induced fit model
n., [ɪnˈduːst fɪt ˈmɑdl̩]
Definition: an enzyme-substrate interaction depicting that both the enzyme and substrate undergo changes to attain an optimal fit
Induced-Fit Model Definition
The induced-fit model is a model for enzyme–substrate interaction to describe that the substrate is capable of inducing the proper alignment of the active site of the enzyme, causing the latter to subsequently perform its catalytic function.
It is opposed to the lock-and-key model that is also used to describe the enzyme-substrate interaction. In the induced fit model, both the substrate and the active site of the enzyme change in conformation until the substrate is completely bound to the enzyme, at which point the final shape and charge is determined. This activates the enzyme into performing its catalytic function.
The induced-fit model was suggested by Daniel Koshland in 1958. It is the more accepted model for enzyme-substrate complex than the lock-and-key model. In the lock-and-key model, the interaction of the substrate and the enzyme is likened to a key (the substrate) that is highly specific to the lock (the active site of the enzyme). It depicts a rather static and rigid form of interaction. Unlike the lock-and-key model, the induced fit model shows that enzymes are rather flexible structures in which the active site continually reshapes by its interactions with the substrate until the time the substrate is completely bound to it.
See the figures below to compare the two. Or, watch the vid below for the differences between the two models.
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