Question

The substrate concentration at which an enzyme attains half of its maximum velocity is

• A. Half life of enzyme
• B. K${}_m$ constant of enzyme
• C. Concentration
• D. None of the above

Answer 1

Answer: (B)

K${}_m$ constant of enzyme

K${}_m$ denotes the Michaelis constant. K${}_m$ is the concentration of substrate at which half the active sites are filled. Thus, K${}_m$ provides a measure of the substrate concentration required for significant catalysis to occur. For most of the enzymes, K${}_m$ is assumed to approximate the substrate concentration at which reaction rate is one half the maximum. K${}_m$ value can be used to compare rate of enzyme catalysis of two different enzymes. Lesser the K${}_m$ value, faster the enzyme.