How does enzyme inhibitor concentration affect the rate of enzyme action?

An enzyme inhibitor is a substance that decreases or completely stops enzyme activity, adversely affecting the rate of enzymatically-catalyzed reactions. Enzyme inhibitors inhibit enzyme reaction either by binding to the enzyme’s active site or to some other region of the enzyme – the allosteric site. This prevents the substrate from binding to the enzyme’s active site, affecting the rate of enzyme-substrate complex formation. 

Enzyme inhibitor concentration is indirectly proportional to the rate of enzyme action. A higher enzyme inhibitor concentration decreases the rate of enzyme action. This is because more enzyme inhibitors bind to the enzyme’s active or allosteric sites, leaving very few or no sites available for the substrate to bind. 

In competitive inhibition, the rate of enzyme action can be increased by increasing the concentration of the substrate in the medium. However, in non-competitive inhibition, the rate of enzyme action cannot be increased, even with an increase in substrate concentration.