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How can an inhibitor slow a chemical reaction?
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reaction mechanism
Possible energy diagram for the dissociation of a covalent molecule, E–N, into its ions E+ and N− (see text).
In chemistry, an inhibitor is a substance that decreases the rate of a chemical reaction, a process sometimes referred to as negative catalysis or retardation. Inhibitors function through several distinct mechanisms depending on the nature of the reaction:1
- Catalyst Poisoning: In catalyzed reactions, an inhibitor may bind to the catalyst, forming a complex that reduces the concentration of the active catalyst available to facilitate the reaction.1
- Reactant Depletion: An inhibitor can react with one of the reactants to form a complex, thereby decreasing the effective concentration of that reactant available for the primary reaction.1
- Chain Reaction Termination: In reactions that proceed via a chain mechanism, an inhibitor can destroy the chain carriers, effectively terminating the reaction sequence.1
- Enzymatic Inhibition: In biological systems, inhibitors specifically target enzymes. This can occur through competitive inhibition, where the inhibitor binds to the enzyme's active site, or noncompetitive inhibition, where the inhibitor binds elsewhere to deform the active site or block it, preventing the substrate from binding or reacting.23