What type of molecules are formed when an amino acid is deprotonated?

When an amino acid is deprotonated, it loses a hydrogen ion (H+), typically from its carboxyl group (-COOH), thereby transforming into an anionic form. In this deprotonated state, the amino group (-NH2) remains protonated, leading to the formation of a zwitterion. A zwitterion is a molecule that has both a positive charge and a negative charge but is overall neutral.

In the case of amino acids, the carboxyl group becomes deprotonated (and thus carries a negative charge), while the amino group retains the proton (and carries a positive charge). This duality is essential in biochemistry as it influences the amino acid's behavior in solutions, its reactivity, and its interaction with other biomolecules.

The presence of both charges allows zwitterions to engage in ionic interactions and hydrogen bonding, which are critical for protein structure and function. Understanding the zwitterionic form of amino acids is crucial when studying protein folding, stability, and interactions within biological systems.