Question

Which statement regarding enzyme inhibition is correct?
A.Competitive inhibition occurs when a substrate completes with enzyme for binding to inhibitor protein
B.Competitive inhibition occurs when the substrate and the inhibitor complete for active site on the enzyme
C.Non- competitive inhibition of an enzyme can be overcome by adding large amount of substrate
D.Non- competitive inhibitors often bind to the enzyme irreversibly

Answer 1

Hint: Enzymes are biological catalysts that are mainly protein molecules and help to speed up the rate of chemical reactions significantly that are taking place within cells. Enzymes are very crucial for life and they serve a wide range of functions inside the body, for example digestion and metabolism. There are three types of enzyme inhibition seen – competitive inhibition, non-competitive inhibition and un-competitive inhibition.

Complete step by step answer:
-A chemical molecule that is structurally similar to the substrate competes with the substrate for binding to the active site. That molecules are called inhibitors.
-The presence of the inhibitor in a reaction helps to decrease the availability of the active site for binding with the substrate which results in the reduced rate of reaction.
This inhibition of inhibition is known as competitive inhibition.
-A famous example of competitive inhibition is – malonate acts as a competitive inhibitor that competes with the succinate and prevents the attachment of succinate to the enzyme succinate dehydrogenase and thus reduce the rate of reaction.
-In non competitive inhibition, inhibitor molecules bind to the site other than the active site and thus induce some changes in the enzyme active site that inhibits the binding of substrate to the active site.

So, the correct answer is option B. Competitive inhibition occurs when the substrate and the inhibitor compete for active site on the enzyme.

Note:
-The binding of the inhibitor with the enzyme is reversible and adding a large amount of substrate may not help to overcome the non- competitive inhibition.