In a Lineweaver-Burk analysis, an inhibitor produces lines that intersect to the LEFT of the y-axis but ABOVE the x-axis. Compared with uninhibited enzyme, the inhibited reaction shows:

• A Increased apparent Km with unchanged Vmax
• B Decreased Vmax with unchanged Km
• C Parallel lines with decreased Km and decreased Vmax
• D Decreased Vmax with altered Km, either increased or decreased ✓

Explanation

Lines intersecting above the x-axis and left of the y-axis indicate mixed inhibition: the inhibitor binds both free enzyme and the ES complex but with different affinities. Vmax always decreases, and apparent Km may increase or decrease depending on whether the inhibitor prefers free enzyme or the ES complex. Pure noncompetitive inhibition gives intersection exactly on the x-axis with unchanged Km. Parallel lines are the signature of uncompetitive inhibition, where both Km and Vmax fall proportionally.

Reference: Lehninger Principles of Biochemistry, 8th ed.

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