4.2.4 Acid base properties of amino acids

4.2.4 Acid-base properties of amino acids

Amino acids contain a carboxyl group (acidic) and an amino group (basic) and hence they behave as acids and bases, that is, they are ampholytes. Glycine, the simplest of all amino acids, can exist in three different ionized states, depending upon the pH of the solution.

Zwitterion

Zwitterion

At around neutral pH, both the α-amino and α-carboxyl groups are ionized. And the molecule is a dipolar or “Zwitterion”. The pH at which the dipolar ion is electrically neutral is called the isoelectric point (pI) and amino acids have no net charge and do not move in an electrical field.

Last modified: Thursday, 10 November 2011, 10:25 AM