Question

Since each enzyme molecule is only able to catalyze a certain number of reactions in a given amount of time, the velocity of the reaction approaches a maximal rate as the substrate concentration increases. The substrate concentration at which the reaction is at half-maximal velocity is called the __________ and has the symbol Km.

Answer 1

The Michaelis-Menten constant (Km) is the substrate concentration where the velocity of an enzyme-catalyzed reaction is at half of the maximum velocity (Vmax). It is a key indicator of an enzyme's affinity for its substrate.

Step-by-step explanation:

The substrate concentration at which the reaction rate has reached half of the maximum velocity is defined as Km, also known as the Michaelis-Menten constant. This parameter is important because it provides insight into the enzyme's affinity for the substrate. A low Km value indicates a high affinity since it means the enzyme can achieve half-maximum velocity at a low substrate concentration. Conversely, a high Km indicates a lower affinity for the substrate. The velocity of an enzyme-catalyzed reaction begins to plateau at a point where increasing the substrate concentration further does not significantly increase the reaction rate because all the enzyme molecules are saturated with the substrate.

Importance of Km and Vmax in Enzymatic Reactions

The two most important kinetic properties of an enzyme are the Km, which is related to how quickly an enzyme becomes saturated with substrate, and the Vmax, the maximum rate of the catalyzed reaction. These values help to describe the efficiency and capacity of enzymes in biological systems.