Non Competitive Inhibitors
Non competitive inhibitor is a type of inhibition of enzymes. Non competitive inhibitor reduces the enzyme activity. In specific, non competitive inhibition is a type of mixed inhibition. The non competitive inhibitor share equal affinity for the enzyme substrate complex and enzyme.
Non competitive inhibition mechanism inhibits the model of a system in such a way that inhibitor and the substrate shall bind to enzymes at any point of time. The substrate and non competitive inhibitor shall bind to the enzyme at any time. The enzyme substrate inhibitor complex will never form a product, whereas the complex shall be converted to either enzyme substrate complex or as enzyme inhibitor complex. The non competitive inhibition is distinguished from mixed inhibition in such a way that the non competitive inhibitor has an equal affinity for both enzyme and enzyme substrate complex.
The most usual and common mechanism of non competitive inhibition includes the reverse binding of non competitive inhibitor to an allosteric site of enzyme. The non competitive inhibitor shall bind directly to the active site of an enzyme. Non competitive inhibition is different from competitive inhibition where the binding of non competitive inhibitor will not prevent the binding of substrate to the enzyme as competitive inhibitor does. It also prevents the formation of product. The non competitive inhibition shall reduce the maximum rate of an enzymatic reaction without any change in apparent catalyst binding affinity for the substrate molecule.
The affinity of apparent enzyme in the presence of non competitive inhibition is equal to the actual affinity of enzyme. The Michaelis Menten kinetics of non competitive inhibition shows that Km app = Km. It is considered as a consequence of Le Chatelier’s Principle as the inhibitor binds to enzyme as well as enzyme substrate complex, it also maintains equilibrium.