Which of the following statements is true regarding enzyme Km?

The statement regarding enzyme Km that is accurate is that most enzymes have a Km that is near the concentration of the substrate. This characteristic is significant in enzymology because Km, or the Michaelis constant, represents the substrate concentration at which the reaction rate is half of the maximum velocity (Vmax) of the enzyme.

When Km is close to the substrate concentration, it suggests that the enzyme operates effectively within that range of substrate availability. This means that enzymes are often well-adapted to their physiological environments, where the concentrations of substrates are typically around the Km value, allowing for efficient catalysis. This is essential for maintaining metabolic pathways under physiological conditions, as it ensures that enzymes can respond rapidly to changes in substrate levels.

The other options do not represent accurate relationships regarding Km. For instance, while low Km values indicate a high affinity between the enzyme and substrate, they do not imply poor interactions; rather, they demonstrate that even at low concentrations of substrate, the enzyme can achieve half of its maximum activity, reflecting effective binding. Thus, understanding Km helps elucidate enzyme kinetics and the relationship between enzyme efficiency and substrate concentration.