In alkaline electrophoresis, proteins migrate toward which electrode?

• A. Cathode
• B. Anode
• C. They do not migrate
• D. They migrate randomly

Answer: (B)

Proteins acquire a net negative charge at alkaline pH because many acidic groups are deprotonated. In electrophoresis, particles move toward the electrode with opposite charge: negatively charged species migrate to the positive electrode, the anode. So, under alkaline conditions, proteins move toward the anode. If the pH were lower than their isoelectric point, they'd be positively charged and would migrate toward the cathode.