Final answer:
A low Km value denotes a high substrate affinity by the enzyme, meaning the enzyme can function efficiently at lower substrate concentrations. Km is derived from the Michaelis-Menten equation, which is central to understanding enzyme kinetics, although it only provides an approximate value of Vmax.
Step-by-step explanation:
The Km (Michaelis constant) value indicates the affinity between an enzyme and its substrate. A low Km implies that the enzyme has a high affinity for the substrate, meaning that the enzyme can achieve half of its maximum velocity (Vmax) at a lower substrate concentration. Conversely, a high Km indicates a weaker affinity, requiring a higher substrate concentration for the enzyme to reach half of its Vmax. The Km is related to the rate constants of catalysis and binding in an enzymatic reaction, and, therefore, it is integral for understanding enzyme efficiency.
The formula for Km arises from the Michaelis-Menten equation, which describes the rate of enzymatic reactions. Additionally, the limitation of the Michaelis-Menten equation is that it provides an approximate value for Vmax rather than an exact value. When the substrate concentration ([S]) is much higher than Km, the rate equation simplifies and the reaction velocity approaches Vmax, indicating that all active sites of the enzyme are occupied by the substrate.