A reversible competitive inhibitor is added to an enzyme reaction. Which kinetic change is expected in the simple competitive-inhibition model?

### Why this is right A competitive inhibitor competes with substrate for enzyme binding. A sufficiently high substrate concentration can overcome this competition, so maximum velocity is unchanged, while more substrate is needed to reach half-maximal velocity. ### The other options - **Apparent Michaelis constant decreases; maximum velocity is unchanged**: the direction of the apparent Michaelis-constant change is reversed. - **Maximum velocity decreases; Michaelis constant is unchanged**: this is more characteristic of pure noncompetitive inhibition in the simple model. - **Both maximum velocity and Michaelis constant decrease**: neither change describes simple competitive inhibition. ### Terms - **Maximum velocity**: the highest reaction rate when enzyme is saturated with substrate. - **Competitive inhibition**: inhibition caused by competition with substrate for enzyme binding. ### Remember Competitive inhibition raises apparent $K_m$ but can be overcome by more substrate.