Competitive inhibition

Competitive Inhibition

Competitive inhibition (/kəmˈpɛtɪtɪv ɪnˈhɪbɪʃən/) is a type of enzyme inhibition where the inhibitor competes with the substrate for binding to the enzyme's active site. The term originates from the Latin words 'competere' meaning 'strive in common' and 'inhibitio' meaning 'holding in'.

Overview

In competitive inhibition, both the inhibitor and the substrate can bind to the enzyme's active site. The inhibitor is similar in structure to the substrate and can bind to the active site, preventing the substrate from binding and thus inhibiting the enzyme's function. This type of inhibition is reversible as the inhibitor can be removed from the active site, allowing the substrate to bind again.

Mechanism

The mechanism of competitive inhibition involves the inhibitor and the substrate competing for the same active site on the enzyme. The inhibitor binds to the active site, forming an enzyme-inhibitor complex, which prevents the substrate from binding to the enzyme. This reduces the rate of enzyme-catalyzed reactions.

Effects

Competitive inhibition increases the Michaelis-Menten constant (Km), which is the substrate concentration at which the reaction rate is half of its maximum. However, it does not affect the maximum rate (Vmax) of the reaction.

Examples

Examples of competitive inhibitors include drugs like statins, which inhibit the enzyme HMG-CoA reductase to lower cholesterol levels, and antibiotics like penicillin, which inhibit bacterial cell wall synthesis.

Related Terms

External links

Medical encyclopedia article on Competitive inhibition
Wikipedia's article - Competitive inhibition

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Competitive inhibition