Non-competative inhibitor

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A non-competitive inhibitor is a reversible inhibitor which binds to the enzyme with weak non-covalent interactions.



Non-competitive inhibition involves the inhibitor binding to an allosteric site on the target enzyme. This binding causes a conformational change of the enzymemolecule to be altered which in turn causes the shape and conformation of the active site to be changed. Therefore, while the inhibitor is bound to the enzyme, the enzyme cannot also form the enzyme-substrate complex which is vital for product formation and thus lowering the activity of the enzyme.

Effect of inhibitor


The Km is unchanged as the enzyme still has the same affinity for the substrate molecule.


The Vmax is decreased as the inhibitor prevents the maximum rate of the chemical reaction being reached, therefore decreasing the efficiency of the enzyme.

Effect of concentration

Non-competitive inhibitors are not affected by changes in substrate concentration, unlike competitive inhibitors.

The extent of inhibition is solely dependent on the concentration of the inhibitor.

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