An example of competitive inhibition of an enzyme is the inhibition of:
Correct answer: A. Succinic dehydrogenase by malonic acid
- A. Succinic dehydrogenase by malonic acid
- B. Cytochrome oxidase by cyanide
- C. Hexokinase by glucose
- D. Carbonic anhydrase by carbon dioxide
Explanation
The inhibition of succinic dehydrogenase by malonic acid is an example of competitive inhibition. Succinic dehydrogenase is an enzyme involved in the citric acid cycle (also known as the Krebs cycle) and plays a role in the conversion of succinate to fumarate. Malonic acid serves as a competitive inhibitor in this context. It structurally resembles the substrate (succinate) and competes with it for binding to the active site of succinic dehydrogenase. Malonic acid binds to the active site of the enzyme, preventing the normal substrate (succinate) from binding and undergoing the catalytic reaction. The presence of malonic acid decreases the rate of the succinic dehydrogenase-catalyzed reaction by interfering with the binding of succinate.
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About Enzymes
Enzymes are biological catalysts that lower activation energy without being consumed, and their specificity is explained by the lock and key and induced fit models. Work includes the effects of temperature, pH and substrate concentration on reaction rate, plus competitive and non-competitive inhibition and how these differ.
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