logo
AAT Bioquest

Are amino acids zwitterionic?

Posted November 8, 2022


Answer

Yes, amino acids are zwitterionic. 

The term zwitterionic refers to the property of carrying both a positive and a negative charge. Amino acids have a positively charged amino group (NH3+) and a negatively charged carboxylic group (COO-). This allows them to act as both an acid and a base at different pH values. When an amino acid is put in an acidic solution, the carboxylic group captures a positively charged hydrogen ion (H+) and the amino acid acquires a positive charge. When the same amino acid is put in an alkaline solution, it loses an H+ ion, acquiring a negative charge. In both instances, the amino acid acts to maintain the pH of the system. Amino acids are the most well-known zwitterions. 

Additional resources

Weak Acid pH Calculator

Dye to Peptide Conjugation

EDANS acid [5-((2-Aminoethyl)amino)naphthalene-1-sulfonic acid]

Zwitterionic versus canonical amino acids over the various defects in zeolites: A two-layer ONIOM calculation

We use cookies to enhance your browser experience and analyze our traffic. By clicking "Accept All", you consent to our use of cookies.

Accept All
Customize
Reject All