The correct answer to this question is option E – Vmax stays the same, KM increase
In competitive inhibitors, the inhibitor looks like the substrate, and it binds to the active site. This, therefore, prevents the substrate from binding.
Vmax represents the maximum velocity of a reaction, and KM represents the amount of substrate that is needed to reach half of Vmax.
The only way to overcome a competitive inhibitor is by adding more substrate. This means more substrate will be required to reach half of Vmax. Thus KM is increased.
Vmax stays the same because the maximum velocity attainable remains the same.
Uncompetitive inhibitions, on the other hand, lower Vmax as well as KM. The inhibitor works by binding to the enzyme-substrate complex.
Non-competitive competition works by binding to an enzyme with or without a substrate. It causes a conformational change in the active site of the enzyme. It lowers Vmax only, and KM remains the same.