Question

Blocking of active site of an enzyme is a kind of

• A. Non-competitive inhibition
• B. Competitive inhibition
• C. Allosteric inhibition
• D. Feed back inhibition

Answer 1

The correct option is B Competitive inhibition

Competitive inhibitors are the substances which compete with the substrates for the active sites of enzyme. Non competitive inhibition is caused by inhibitor action which is non-competitive, i.e., competitor will not compete for the binding at active site of the enzyme. Allosteric modulators are the one which bind to a separate allosteric site on the enzyme and do not compete for the active site. Usually binding of an allosteric modulator brings about conformational changes in the enzyme which can increase the reaction rate (positive allosteric modulation) or decrease the reaction rate (negative allosteric modulation).
Feedback inhibition is a term used to denote the inhibition of enzymes in a multistep chain or a metabolic pathway in which product of one reaction is the substrate of next reaction. Accumulation of a product of any reaction will inhibit the previous enzymes.