Final answer:
The nitrogen in the histidine ring is a weaker base than the α-amino group due to the difference in pKa values.
Step-by-step explanation:
The nitrogen in the histidine ring is a weaker base than the α-amino group because of the difference in the pKa values. The α-amino group has a pKa value around 9, while the amine group in the histidine side chain has a pKa value of 6.04. A lower pKa value indicates a stronger acid or weaker base. The difference in pKa values suggests that the α-amino group is more likely to accept a proton and act as a base compared to the amine group in the histidine ring.