Final answer:
Alanine will remain neutral and stationary since the buffer is set to its isoelectric point. Glutamic acid, with a lower isoelectric point, will carry a positive charge and move towards the cathode. Arginine, with a higher isoelectric point, will carry a negative charge and move towards the anode.
Step-by-step explanation:
When an electric current is passed through an aqueous solution of a mixture of amino acids buffered at a specific pH, the charge on each amino acid will determine its movement. The isoelectric point (pI) of an amino acid is the pH at which the amino acid has no net electrical charge, thus not moving under the influence of an electric field.
For alanine with a pI of 6.0, since the buffer is at pH 6, alanine will be at its isoelectric point and will remain neutral, not moving in the electric field. Glutamic acid, with a pI of 3.2, will be protonated and carry a net positive charge at this pH, causing it to migrate towards the cathode (-ve electrode). Arginine has a pI of 10.7 which means that at pH 6, it will be deprotonated and carry a net negative charge, hence it will migrate towards the anode (+ve electrode).