Competitive inihition at lower substrate concentration

Since the concentrations of substrate and inhibitor are similar at lower substrate concentrations, both the substrate and the competitive inhibitor can bind to the active site of the enzyme. You can see below that at lower substrate concentrations some of the enzyme is involved in catalysis and some of the enzyme is binding inhibitor and no catalysis occurs. Thus in the presence of inhibitor the rate of reaction will be lower than in the absence of inhibitor since in the absence of inhibitor all of the enzyme molecules would be invovled in catalysis.


 inhibitor present

 inhibitor absent

return to competitive inhibition