Question

With regard to its effect on an enzyme-catalyzed reaction, a competitive inhibitor
a)Lowers the KM only
b) Lowers the KM and lowers the Vmax
c)Raises the KM only
d) Raises the KM and lowers the Vmax
e)Raises the KM and raises the Vmax

Answer 1

Vmax is the maximum velocity of the enzyme. Competitive inhibitors can only bind to E and not to ES. They increase Km by interfering with the binding of the substrate, but they do not affect Vmax because the inhibitor does not change the catalysis in ES because it cannot bind to ES.