A mixture containing Aspartic acid, Arginine, and Alanine is placed in an electrophoretic cell buffered at a pH of 6.0. Under the applied electric field, what will be the respective directions of migration for Aspartic acid, Arginine, and Alanine?

Step-by-step solution

The direction of migration of an amino acid in an electric field depends on the pH of the medium relative to its isoelectric point (pI). Alanine is a neutral amino acid with a pI of approximately 6.0. At pH = 6.0, pH pI, so it exists primarily as a neutral zwitterion with zero net charge. It will remain largely stationary. Aspartic acid is an acidic amino acid with a pI of approximately 3.0. At pH = 6.0, the pH is greater than its pI (pH > pI). It will lose protons to form an anion (net negative charge) and migrate