Question

Which of the following best explains why arginine is more basic than lysine?

A. The electron-donating groups around the basic nitrogen on arginine make its conjugate base less stable.
B. The electron-donating groups around the basic nitrogen on arginine make its conjugate acid more stable.
C. The lack of electron-donating groups on lysine make its conjugate acid more stable.
D. The lack of electron-withdrawing groups on lysine make its conjugate base more stable.

Answer 1

B. The electron-donating groups around the basic nitrogen on arginine make its conjugate acid more stable.

Step-by-step explanation:

The basic nature of a compound can be analized with the stability of its conjugate acid. The more stable the conjugate acid is, the more basic the substance is.

With that information in mind the answer is either B. or C.

Finally, in the structure of lysine we see that there are other electron donating groups (such as an amine or an imine), so the answer is option B.