Final answer:
Enzymes with low substrate affinity approach Vmax more closely than enzymes with high substrate affinity at subsaturating substrate concentrations.
Step-by-step explanation:
In an enzyme-catalyzed reaction, the velocity more closely approaches Vmax when the enzyme has low substrate affinity rather than high substrate affinity at any given subsaturating substrate concentration.
When an enzyme has low substrate affinity, it requires a higher substrate concentration to reach Vmax because the active sites of the enzyme are less likely to be occupied by substrate molecules. On the other hand, when an enzyme has high substrate affinity, it can reach Vmax at a lower substrate concentration because the active sites of the enzyme are more likely to be occupied by substrate molecules.
Therefore, enzymes with low substrate affinity have a higher rate of reaction at subsaturating substrate concentrations compared to enzymes with high substrate affinity.