Table of contents

1. Introduction to Biochemistry4h 34m
2. Water3h 23m
3. Amino Acids8h 10m
4. Protein Structure10h 4m
5. Protein Techniques14h 5m
6. Enzymes and Enzyme Kinetics13h 38m
7. Enzyme Inhibition and Regulation 8h 42m
8. Protein Function 9h 41m
9. Carbohydrates7h 49m
10. Lipids5h 49m
11. Biological Membranes and Transport 6h 37m
12. Biosignaling9h 45m
Review 1: Nucleic Acids, Lipids, & Membranes2h 47m
Review 2: Biosignaling, Glycolysis, Gluconeogenesis, & PP-Pathway3h 12m
Review 3: Pyruvate & Fatty Acid Oxidation, Citric Acid Cycle, & Glycogen Metabolism2h 26m
Review 4: Amino Acid Oxidation, Oxidative Phosphorylation, & Photophosphorylation1h 48m

7. Enzyme Inhibition and Regulation

Enzyme Inhibition

Biochemistry

7. Enzyme Inhibition and Regulation

Enzyme Inhibition

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Multiple Choice

A noncompetitive inhibitor decreases the rate of an enzyme reaction by:

increasing the affinity of the enzyme for its substrate

binding irreversibly to the substrate, preventing its conversion to product

competing with the substrate for the active site, thereby increasing the K_m

binding to an allosteric site and reducing the maximum velocity (V_{max}) of the reaction

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Verified step by step guidance

Understand the concept of enzyme inhibition: Noncompetitive inhibitors bind to an allosteric site, which is a site other than the active site of the enzyme. This binding alters the enzyme's structure or function, reducing its ability to catalyze the reaction.

Recognize the key effect of noncompetitive inhibition: Unlike competitive inhibitors, noncompetitive inhibitors do not compete with the substrate for the active site. Instead, they reduce the maximum velocity (V_{max}) of the reaction without affecting the substrate's binding affinity (K_m).

Analyze the mechanism: When a noncompetitive inhibitor binds to the allosteric site, it changes the enzyme's conformation, making it less effective at converting substrate into product. This decreases the overall catalytic efficiency of the enzyme.

Compare the options provided: Evaluate each statement in the problem. The first three options describe mechanisms that are not characteristic of noncompetitive inhibition. The correct answer is the fourth option, which states that the inhibitor binds to an allosteric site and reduces V_{max}.

Summarize the impact: Noncompetitive inhibition is characterized by a decrease in V_{max} while K_m remains unchanged. This is because the inhibitor affects the enzyme's activity regardless of substrate concentration, as it does not interfere with substrate binding directly.