Biology as Poetry: Biochemistry

Bacteriophage Ecology Group

Induced Fit

Hypothesis that upon binding, active sites change their conformation to accommodate substrates.

The induced fit hypothesis contrasts with that of the lock and key hypothesis where instead an assumption is made that the active site possesses a substrate-fitting shape prior to substrate binding. One view of induced fit is that it is the first step of the process of enzyme-mediated catalysis, i.e., where substrate binding "induces" a series of conformational changes in enzymes that serve to facilitate substrate chemical modification.

The "product" of either lock and key or induced fit mechanisms of enzyme-substrate interaction is what is known as the enzyme-substrate complex. Catalysis thus involves substrate(s) movement relative to the enzyme such as by diffusion, collision with the enzyme active site, induced fit resulting in formation of the enzyme-substrate complex, catalysis, and then release of product(s). The overall time required to go from induced fit to product release is equivalent to an enzyme's turnover rate.

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