Chapter 18, Problem 18.26QP

Interpretation Introduction

Interpretation:

The reason for amino acids to act as zwitterions at $\text{pH}$7 has to be explained.

Concept Introduction:

All the amino acids in water exist as dipolar species in which the amino group contains a protonated amino group $\left(-{\text{NH}}_3^{+}\right)$ and a carboxylic group that lost its proton $\left(-{\text{COO}}^{-}\right)$. The name given to this dipolar amino acid is zwitterion. A zwitterion is a species that contains an equal number of positive ion and negative ions.

The general structure of a zwitterion is,