Question

What is the consequence of a high Km value of an enzyme? 

• High concentration of the substrate is needed for the maximal enzyme activity. 

• The enzyme is present in a large concentration in the cell. 

• Moderate concentration of the substrate will be enough for maximal enzyme activity. 

• This enzyme has high maximal velocity. 

Answer 1

Answer) High concentration of the substrate is needed for the maximal enzyme activity.

The consequence of having a high K_m value for enzymes is that it needs high concentration of the substrate for it's activity. Those enzymes which have high K_m values will have low affinity for its substrate and the saturation with substrate is low and as a result more addition of substrate concentration is necessary. The K_m value( Michaelis constant) can be defined as the concentration of substrate were the reaction rate will be half of its maximal value. The K_m value of substrate will help the enzyme to achieve the Vmax. Vmax is the point where the substrate and enzymes are completely saturated. An enzyme with low K_m value will have a high affinity for substrate and will be easily saturated with substrate.For a reaction to occur, it is important to know about the K_m value and the Vmax value because sometimes the rate of production of products will be dependent on the substrate concentration.

The other options are wrong because K_m value is not the indicator of concentration of enzyme, it is the concentration of substrate and also high K_m value of enzymes need high concentration of substrate, not in moderate amounts. To achieve high maximal velocity the saturation of substrate and enzymes should be faster.