Question

Which of the following statement is incorrect for maximum velocity (V${}_{max}$) of an enzyme catalysed reaction?

• A. It is not a fundamental property of an enzyme, since it is dependent on the initial enzyme loading.
• B. It is measured for the purpose of enzyme assay.
• C. It can be converted into the reaction velocity at a lower substrate concentration.
• D. It can be used to deduce the number of active catalytic sites per enzyme molecule.

Answer 1

The correct option is B It is measured for the purpose of enzyme assay.

V${}_{max}$ or maximum velocity of enzyme catalyzed reaction is a fundamental characteristic of enzyme. It depends on the number of active sites in enzymes and can be directly correlated with the substrate concentration at lower substrate concentration. In other words, at low substrate concentration, the V${}_{max}$ of a reaction will increase with the concentration of substrate molecules till all the available active sites are saturated with the substrate molecules. However, it is difficult to exactly calculate V${}_{max}$. Hence, V${}_{max}$ is not a measure for the purpose of enzyme assay. It is usually deduced graphically. The reaction rate is measured at different substrate concentration and a graph is drawn. From the graph, V${}_{max}$ and optimum substrate concentration can be deduced.

Therefore, the correct answer is option B.