Question

Following graphs show the effect of change in concentration of substrate on enzyme activity:
Graph - A:

Graph - B:

Graph - C:

Graph - D:

In which of the above curve, the enzyme shows maximum substrate affinity?

• A. Graph - A
• B. Graph - B
• C. Graph - C
• D. Graph - D

Answer 1

Answer: (B)

K_m indicates the affinity of the enzyme towards its substrate.
$Km \, = \, \frac{1}{2} \, V_{m a x}$
K_m value differs from substrate to substrate because different enzymes differ in their affinity towards different substrates. A high K_m indicates low affinity, whereas a low K_m shows strong affinity. Out of the given graphs, K_m value is lowest in this option and hence shows maximum substrate affinity.