Which one and why Thank you Answer was not B The enzyme acti

Which one and why? Thank you. Answer was not B.

The enzyme activity of the protease elastase was studied with three artificial substrates. The enzyme has the highest catalytic efficiency with which substrate? A) 1 B) 2 C) 3 D) all bind with the same affinity

Solution

enzyme has highest catalytic efficiency with substrate 3.

enzyme 3 has lowest Km with substrate 3. this indicates highest binding affinity towards substrate 3.

since the Kcat value is also given, we have to consider both Km and Kcat.

enzyme efficiency depends on Kcat/Km. It is 6.5 for substrate 1, 24.6 for substrate 2 and 28.12 for substrate 3.

Therefore, it is substrate 3.