In a Lineweaver-Burk analysis, an inhibitor produces lines that intersect at a single point to the LEFT of the y-axis, not on either axis. The apparent Km increases while Vmax decreases. This pattern indicates:
- A Pure competitive inhibition
- B Pure non-competitive inhibition
- C Mixed inhibition, with different affinities of the inhibitor for the free enzyme and the enzyme-substrate complex ✓
- D Uncompetitive inhibition
Correct answer: C. Mixed inhibition, with different affinities of the inhibitor for the free enzyme and the enzyme-substrate complex
Explanation
Mixed inhibition occurs when the inhibitor binds both free enzyme and the ES complex but with unequal affinity. Both slope and y-intercept change, so lines intersect above or below the x-axis but to the left of the y-axis, and both apparent Km and Vmax are altered. Pure competitive lines meet on the y-axis, pure non-competitive on the x-axis, and uncompetitive lines are parallel, so none of those patterns fits the described intersection point.
Reference: Lippincott Illustrated Reviews: Biochemistry, 8th ed.
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