What is the Origin of Zwitterionic State?

This term is rooted in physical chemistry, deriving from the German word Zwitter, meaning "hermaphrodite" or "hybrid," reflecting the molecule's dual charge. The concept is foundational to protein chemistry and the behavior of amphoteric molecules. Understanding the zwitterionic state is crucial for biochemical separation techniques like electrophoresis.

What is the Mechanism of Zwitterionic State?

For an amino acid, the zwitterionic state is achieved when the carboxyl group (COOH) is deprotonated to form the negatively charged carboxylate ion (COO-) and the amino group (NH2) is protonated to form the positively charged ammonium ion (NH3+). These two charges neutralize each other within the molecule. The transition to and from this state is governed by the surrounding solution's pH and the pKa values of the ionizable groups.

Zwitterionic State ∞ Area

Zwitterionic State

Meaning

The zwitterionic state describes the specific molecular condition of a compound, most notably an amino acid, where it simultaneously carries both a positive and a negative electrical charge, resulting in a net electrical charge of zero. This unique dipolar ion structure exists predominantly in aqueous solution at a characteristic pH known as the isoelectric point (pI). This state is essential for the solubility and functional properties of biological molecules.