Michaelis–Menten: velocity at a given [S]
For an enzyme following Michaelis–Menten kinetics, what is the reaction velocity when [S] = 3Km?
Answer C: explanation for every choice
A
This inverts the equation, giving Km/(Km + [S]).
B
Half of Vmax occurs when [S] = Km.
C
Correct. v = Vmax[S]/(Km + [S]) = 3Km/4Km = 0.75 Vmax.
D
Vmax is only approached at saturating substrate concentrations.
Takeawayv = Vmax[S]/(Km + [S]). At [S] = Km, v = ½Vmax.
Equation usedMichaelis–Menten
Next question →Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb31.