In: Biology
Sulfanilamide that resembles substrate of an enzyme inhibits the enzyme when added to the reaction mix. What type of inhibition is this
A) allosteric inhibition
B) competitive inhibition
C) excitatory allosteric control
D) noncompetitive inhibition
E) feedback inhibition
Answer : B. Competitive inhibition
Explanation : Competitive inhibition is a process where a molecule which resembles the substrate of an enzyme, compete with the substrate to bind with the enzyme, usually at active site, and upon binding prevents the binding of substrate with the enzyme resulting inhibition of the process to be mediated by that particular enzyme. In non-competitive inhibition, the inhibitor molecule binds to the enzyme somewhere else other than the active site, and changes the three-dimensional structure of the active site where the substrate can still bind with usual affinity, but the enzyme cannot catalyse the reaction with proper stability. In case of feedback inhibition, the activity of the enzyme is inhibited by the enzyme's own end product. In allosteric inhibition, an effector molecule binds at a site of enzyme other than its active site which consequently changes the conformation of enzyme's active site making it unable to bind with proper substrate.
In this case, sulfanilamide resembles to the substrate of an enzyme and inhibits the function of enzyme when added to the reaction mix. So, it is clear that sulfanilamide is competing with the substrate to bind at the active site of the enzyme as it resembles to the substrate, and upon binding it stops or inhibits the reaction. So, it is a type of competitive inhibition.
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