Final answer:
A substrate-enzyme system with a KM value of 10 to the power of -6 reflects a high affinity, as lower KM values indicate stronger binding between the enzyme and substrate. Therefore, correct option is a.
Step-by-step explanation:
A substrate-enzyme system with a KM value of 10 to the power of -6 (which is 0.000001 or 1 micromolar) indicates a high affinity between the enzyme and the substrate.
This is because a low KM value suggests that the enzyme can effectively bind with the substrate at low concentrations, thereby being efficient in its catalytic action even when the substrate is scarce. Conversely, a high KM value would indicate a weaker binding affinity and thus lower efficiency at low substrate concentrations.
In enzymatic reactions, as the substrate concentration reaches KM, the velocity of the reaction is at half the maximum velocity (1/2Vmax). A KM value in the micromolar range is typically considered to be indicative of a high-affinity interaction between the enzyme and its substrate.