Non-competative inhibitor
Non-competitive inhibition
A non-competitive inhibitor is a reversible inhibitor which binds to the enzyme with weak non-covalent interactions.
Mechanism
Non-competitive inhibition involves the inhibitor binding to an allosteric site on the target enzyme. This binding causes the shape of the enzyme molecule 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
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 enzymes efficiency.
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.