The pH at which an amino acid exists mainly as a zwitterion and does not migrate in an electric field is called its

Explanation

At the isoelectric point the positive and negative charges within the molecule exactly balance, so the net charge is zero and the amino acid is at its least soluble and does not move towards either electrode. The value differs for each amino acid according to its side chain. Electrophoresis separates amino acids and proteins by exploiting these differences.