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Multiple Choice
In the context of enzyme-catalyzed reactions, how does a noncompetitive inhibitor reduce an enzyme's activity?
A
By increasing the enzyme's affinity for the substrate.
B
By binding to the active site and preventing substrate binding.
C
By binding to an allosteric site, altering the enzyme's conformation and reducing its activity.
D
By competing with the substrate for the active site.
Verified step by step guidance
1
Understand the role of enzymes: Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy. They have specific active sites where substrates bind.
Define noncompetitive inhibition: A noncompetitive inhibitor binds to an enzyme at a site other than the active site, known as an allosteric site. This binding changes the enzyme's shape.
Explain the effect of noncompetitive inhibitors: When a noncompetitive inhibitor binds to the allosteric site, it alters the enzyme's conformation, which can reduce the enzyme's activity regardless of the substrate concentration.
Differentiate from competitive inhibition: Unlike competitive inhibitors, which compete with the substrate for the active site, noncompetitive inhibitors do not prevent substrate binding directly but still reduce the enzyme's overall activity.
Summarize the impact on enzyme kinetics: Noncompetitive inhibition decreases the maximum reaction rate (Vmax) without affecting the substrate's affinity for the enzyme, as the inhibitor does not compete with the substrate for the active site.