Enzyme Kinetics II: Competitive Inhibition

Abstract

A competitive inhibitor combines with the enzyme and inhibits its catalytic activity. The inhibitory activity is reversed if the substrate concentration is increased. If the inhibition is due to the inhibitor combining with the active site of the enzyme in such a way as to prevent substrate combination then, for a fixed concentration I of inhibitor, the double-reciprocal relation, l/v against 1/[S], is given by

$$\frac{1}{v} = \frac{{{K_M}}}{{{V_{\max }}}}\;\left( {1 + \frac{I}{{{K_I}}}} \right)\frac{1}{{[S]}} + \frac{1}{{V\max }}.$$

((19.1))