Question:
Some of the exceptional properties of regulatory/allosteric enzymes are:
(A) Their Kinetics do not obey the Michaelis-Menten equation.
(B) They are mostly monomeric in nature.
(C) They have more than one substrate binding sites and the substrate binding to different sites is mutually independent, exclusive and noncooperative.
(D) Binding of effector molecules to them may lead to their activation or inhibition.
Some of the exceptional properties of regulatory/allosteric enzymes are:
(A) Their Kinetics do not obey the Michaelis-Menten equation.
(B) They are mostly monomeric in nature.
(C) They have more than one substrate binding sites and the substrate binding to different sites is mutually independent, exclusive and noncooperative.
(D) Binding of effector molecules to them may lead to their activation or inhibition.
(A) Their Kinetics do not obey the Michaelis-Menten equation.
(B) They are mostly monomeric in nature.
(C) They have more than one substrate binding sites and the substrate binding to different sites is mutually independent, exclusive and noncooperative.
(D) Binding of effector molecules to them may lead to their activation or inhibition.
Show Hint
Allosteric enzymes are multimeric proteins that display sigmoidal kinetics (violating Michaelis-Menten kinetics) due to cooperativity, and they are regulated by allosteric activators or inhibitors.
Updated On: Jul 23, 2026
- (A), (B) and (D) only.
- (A), (C) and (D) only.
- (A), (B), (C) and (D).
- (A) and (D) only.
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The Correct Option is D
Solution and Explanation
Step 1: Understanding the Concept:
Allosteric enzymes are regulatory enzymes whose catalytic activity is modulated by the non-covalent binding of specific regulatory molecules (effectors) at sites other than the active site (allosteric sites).
Step 2: Detailed Explanation:
Let us analyze each statement to determine the characteristics of allosteric enzymes:
- (A) Their Kinetics do not obey the Michaelis-Menten equation: This is correct.
Instead of a hyperbolic curve, allosteric enzymes exhibit a sigmoidal (S-shaped) curve when initial velocity is plotted against substrate concentration.
- (B) They are mostly monomeric in nature: This is incorrect.
Allosteric enzymes are almost exclusively oligomeric, consisting of multiple subunits (polypeptide chains) that allow for cooperative interactions.
- (C) Substrate binding is mutually independent and noncooperative: This is incorrect.
Substrate binding to one subunit of an allosteric enzyme typically influences the conformation of other subunits, showing cooperative binding behavior.
- (D) Binding of effector molecules may lead to their activation or inhibition: This is correct.
Allosteric activators or inhibitors bind to specific regulatory sites, shifting the conformational equilibrium between the active state (R-state) and inactive state (T-state) of the enzyme.
Thus, only statements (A) and (D) represent correct properties of allosteric enzymes.
Step 3: Final Answer:
The properties associated with regulatory/allosteric enzymes are (A) and (D) only.
Allosteric enzymes are regulatory enzymes whose catalytic activity is modulated by the non-covalent binding of specific regulatory molecules (effectors) at sites other than the active site (allosteric sites).
Step 2: Detailed Explanation:
Let us analyze each statement to determine the characteristics of allosteric enzymes:
- (A) Their Kinetics do not obey the Michaelis-Menten equation: This is correct.
Instead of a hyperbolic curve, allosteric enzymes exhibit a sigmoidal (S-shaped) curve when initial velocity is plotted against substrate concentration.
- (B) They are mostly monomeric in nature: This is incorrect.
Allosteric enzymes are almost exclusively oligomeric, consisting of multiple subunits (polypeptide chains) that allow for cooperative interactions.
- (C) Substrate binding is mutually independent and noncooperative: This is incorrect.
Substrate binding to one subunit of an allosteric enzyme typically influences the conformation of other subunits, showing cooperative binding behavior.
- (D) Binding of effector molecules may lead to their activation or inhibition: This is correct.
Allosteric activators or inhibitors bind to specific regulatory sites, shifting the conformational equilibrium between the active state (R-state) and inactive state (T-state) of the enzyme.
Thus, only statements (A) and (D) represent correct properties of allosteric enzymes.
Step 3: Final Answer:
The properties associated with regulatory/allosteric enzymes are (A) and (D) only.
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