What characterizes a zwitterion?

A zwitterion is characterized by the presence of both a positive and a negative charge, while overall maintaining a net neutral charge. This unique balance occurs because zwitterions contain functional groups that can both donate and accept protons, thus creating a dipolar ion. A common example is an amino acid at physiological pH, where the amino group (–NH3⁺) carries a positive charge, while the carboxyl group (–COO⁻) carries a negative charge.

The presence of both charges is critical in defining the properties of zwitterions, such as their solubility and behavior in different environments, such as during electrophoresis. Zwitterions play a significant role in biological systems, particularly in the structure and function of proteins and enzymes. The net neutrality ensures that these molecules can move through biological membranes without being repelled or attracted by charges.

Understanding zwitterions is fundamental when studying amino acids and other biomolecules in biochemistry, making it essential to recognize their unique charge characteristics.