Question

Competitive inhibitor of an enzyme
[NCERT Pg. 158]
(1) Increases Km value of substrate for that
enzyme
(2) Decreases Km value of substrate for that
enzyme
(3) Decreases V
value of the enzymatic
reaction
max
(4) Increases V.
value of the enzymatic reaction
max​

Answer 1

Explanation:

Measurements of the rates of catalysis at different concentrations of substrate and inhibitor serve to distinguish the two types of inhibition. In competitive inhibition, the inhibitor competes with the substrate for the active site. The dissociation constant for the inhibitor is given by



Because increasing the amount of substrate can overcome the inhibition, Vmax can be attained in the presence of a competitive inhibitor (Figure 8.17). The hallmark of competitive inhibition is that it can be overcome by a sufficiently high concentration of substrate. However, the apparent value of KM is altered; the effect of a competitive inhibitor is to increase the apparent value of KM. This new value of KM, called KappM , is numerically equal to