From most anodal to least, what is the order of amylase isoenzyme mobility?

• A. S1, S2, S3, P1, P2, P3
• B. P3, P2, P1, S3, S2, S1
• C. S3, S2, S1, P3, P2, P1
• D. S1, P1, S2, P2, S3, P3

Answer: (A)

In electrophoresis, molecules migrate toward the anode (positive electrode) if they carry a net negative charge at the run pH; the greater the negative charge, the faster the migration toward the anode. Amylase exists in different isoforms, with salivary (S) forms generally carrying more negative charge than pancreatic (P) forms, and the subtypes differ slightly in charge within each group. Among the salivary isoforms, S1 has the highest negative charge and thus moves closest to the anode, followed by S2, then S3. Within the pancreatic group, P1 is more negatively charged than P2, which is more than P3. Putting it together, the order from most anodal to least is S1, S2, S3, P1, P2, P3.