Free enzyme concentration in kinetics graphs

Steps:

• Identify components: graphs track substrate (decreases), product (increases), ES complex (transient rise), and free enzyme (initial drop).
• Free enzyme starts at total [E], binds substrate to form ES, so its concentration falls quickly.
• During steady-state catalysis, free [E] remains low until product release.
• Match line to pattern: high initial value that declines and plateaus low.

Why B is correct:

• Line B shows high starting concentration that drops rapidly and stays low, aligning with free enzyme depletion in Michaelis-Menten model where [E_free] = [E_total] - [ES].

Why the others are wrong:

• A: Steady decline matches substrate consumption, not enzyme.
• C: Gradual rise indicates product formation over time.
• D: Initial rise then fall represents transient ES complex buildup and breakdown.

Final answer: B