Vmax is proportional to enzyme concentration.

Vmax is proportional to enzyme concentration.

• A. Vmax is independent of enzyme concentration.
• B. Vmax increases with increasing enzyme concentration.
• C. Vmax decreases with increasing enzyme concentration.
• D. Vmax depends only on substrate concentration.

Answer: (B)

Vmax is the maximum rate of an enzyme-catalyzed reaction when the substrate is abundant enough that all enzyme molecules are working as fast as they can. In this saturated state, the overall rate is limited by how quickly each enzyme molecule can turnover substrate, which is the turnover number kcat. The total capacity to process substrate is then Vmax = kcat [E]t, where [E]t is the total enzyme concentration. That means more enzyme molecules mean more active sites available, so the maximum achievable rate increases in direct proportion to enzyme concentration. If you increase enzyme concentration, Vmax goes up proportionally (assuming substrate is in excess and the enzyme remains active). Km, the measure of substrate affinity, is independent of enzyme concentration, which is why conclusions focusing only on substrate concentration don’t capture the full picture of Vmax.

Vmax is the maximum rate of an enzyme-catalyzed reaction when the substrate is abundant enough that all enzyme molecules are working as fast as they can. In this saturated state, the overall rate is limited by how quickly each enzyme molecule can turnover substrate, which is the turnover number kcat. The total capacity to process substrate is then Vmax = kcat [E]t, where [E]t is the total enzyme concentration. That means more enzyme molecules mean more active sites available, so the maximum achievable rate increases in direct proportion to enzyme concentration. If you increase enzyme concentration, Vmax goes up proportionally (assuming substrate is in excess and the enzyme remains active). Km, the measure of substrate affinity, is independent of enzyme concentration, which is why conclusions focusing only on substrate concentration don’t capture the full picture of Vmax.