At a physiological pH of 7.4, amino acids exist as zwitterions. At a very low pH (in an acid solution), both the amine group and the carboxylic acid group on an amino acid are protonated. Therefore, the following must be true: the pK_a of the ________ group is larger than the pK_a of the ________ group.

Question

Quizplus · Accepted Answer

The pKa of the protonated amine group is larger than the pKa of the carboxylic acid group, meaning the carboxylic acid group loses its proton first as the pH increases from a very low value.

At a Physiological PH of 7