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How does an inhibitor slow down a chemical reaction?
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catalysis
Nanoparticles of a gold-palladium (yellow-blue) alloy supported on acid-treated carbon (gray) directly catalyzing hydrogen peroxide formation from hydrogen (white) and oxygen (red) while shutting off unwanted hydrogen peroxide decomposition.
An inhibitor slows down a chemical reactionâa process known as inhibition or negative catalysisâby decreasing the rate at which the reaction occurs. This can happen through several distinct mechanisms:1
- Reactant Depletion: The inhibitor may form a complex with a reactant, effectively reducing its concentration.1
- Catalyst Poisoning: The inhibitor may bind to an active catalyst, forming a complex that renders the catalyst inactive.1
- Chain Reaction Termination: In certain reactions, the inhibitor destroys chain carriers, thereby halting the chain reaction.1
- Enzyme Inhibition: In biological systems, inhibitors can block enzymes by:
- Competitive Inhibition: The inhibitor competes with the substrate for the active site, preventing the substrate from binding.23
- Irreversible Inhibition: The inhibitor reacts with groups at the active site, often forming a covalent bond that permanently blocks catalysis.2
- Allosteric/Noncompetitive Inhibition: The inhibitor binds to a site other than the active site, causing a change in the enzyme's shape that misaligns the catalytic groups, preventing the reaction even if the substrate can still bind.4