Enzymes
The Michaelis–Menten equation for enzyme kinetics is: v = (Vmax [S]) / (Km + [S]). When the substrate concentration [S] equals Km, the reaction velocity v is:
Select the correct option:
Solution
Vmax/2
Substituting [S] = Km into the Michaelis–Menten equation: v = (Vmax × Km) / (Km + Km) = (Vmax × Km) / (2Km) = Vmax/2. Therefore, Km is defined as the substrate concentration at which the reaction rate is exactly half the maximum velocity (Vmax). A lower Km indicates higher affinity of the enzyme for its substrate.
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About This Question
- Subject
- chemistry
- Chapter
- biomolecules
- Topic
- enzymes
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
Vmax/2
Substituting [S] = Km into the Michaelis–Menten equation: v = (Vmax × Km) / (Km + Km) = (Vmax × Km) / (2Km) = Vmax/2. Therefore, Km is defined as the substrate concentration at which the reaction rate is exactly half the maximum velocity (Vmax). A lower Km indicates higher affinity of the enzyme for its substrate.
This medium difficulty chemistry question is from the chapter biomolecules, covering the topic of enzymes. It appeared in the 2025 exam.
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