COMPETITIVE INHIBITION (ENZYME)
In this type of inhibition, the inhibitor shows structural resemblance to the substrate molecules and is regarded as a substrate analogue.
The inhibitor competes with the substrate to bind at the active site of the enzyme.
When an inhibitor binds to the active site of the enzyme, then a stable enzyme-inhibitor complex is formed and the enzyme activity is reduced.
Enzyme + Inhibitor ―――→ Enzyme-Inhibitor Complex
As long as the inhibitor occupies the active site, the enzyme is not available for the active site to bind.
In competitive inhibition, the value of Km increases, while Vmax remains unchanged.
Competitive inhibition is a reversible type of inhibition which can be reversed by increasing the substrate concentration.
A classic example of competitive inhibition is the enzyme Succinate dehydrogenase (SDH) which oxidizes succinic acid to fumaric acid.
Malonic acid (Malonate) shows structural resemblance to succinic acid and competes with the substrate for binding to the active site of Succinate dehydrogenase (SDH).