Final answer:
An enzyme with higher substrate affinity has a lower KM, indicating that it binds more tightly and efficiently to the substrate and requires a lower substrate concentration to reach half its maximum catalytic rate.
Step-by-step explanation:
An enzyme that exhibits higher affinity for its substrate will have a lower KM. This is because KM represents the substrate concentration at which the reaction rate is half its maximum (Vmax), and a lower KM value indicates that the enzyme achieves half-maximum catalytic activity at a lower substrate concentration, reflecting stronger binding to the substrate.
Enzymes with a high KM value have weaker binding to the substrate, meaning they need a higher substrate concentration to reach half of their maximum catalytic activity. It is important to note that the binding portion of enzyme kinetics, represented by k1, is independent of the enzyme's catalytic rate. However, when an enzyme binds more tightly with its substrate, this increased efficiency in binding typically correlates with a decreased KM value, which is indicative of a higher substrate affinity.