C.7.3

When the substrate concentration increases
Initially as the substrate concentration increases the rate of the reaction increases because there are many active sites available on the enzyme for the substrate to react with. Increasing the substrate increases the frequency of collisions between the substrate and the active site on the enzyme. Eventually as the active site become occupied (saturated), the rate of the reaction will start to decrease until a maximum rate called Vmax is reached. Vmax is significant because at Vmax all the active sites are used up by the substrate and so the rate of the reaction cannot increase any further with increasing substrate. V max is the maximum rate of reaction reached when the substrate concentrations are higher. The V max represents enzyme saturation since is shows that once all the sites are used up for an enzyme at high concentrations, the enzyme cannot work any faster and thus reaches a maximum rate of reaction.

The Michaelis-Menten constant Km is the affinity of the substrate for the enzyme. Km is equal to the substrate concentration when the rate of the reaction is 0.5 V max. Km is significant because it will always be the same for a particular enzyme with a particular substrate, and thus, it indicates whether the enzyme functions efficiently at low or higher substrate concentrations (i.e. indicating whether high substrate concentrations are necessary for efficient catalyzation)

Vmax/Km measures enzyme efficiency and all enzymes can be compared by using it.