INFLUENCE OF SINGLE AMINO-ACID SUBSTITUTIONS ON ELECTROPHORETIC MOBILITY OF SODIUM DODECYL SULFATE PROTEIN COMPLEXES

The substitutions Thr → Ala, Gln → Leu and Pro → Thr or Ala in mammalina α-crystallin A chains (19,830 daltons) are found to increase the electrophoretic mobility in sodium dodecyl sulfate gel electrophoresis. Substitutions between residues of like hydrophobicity and small changes in intrinsic charge of the chain did not alter the mobility. Changes in hydrophobicity appear to influence the binding of sodium dodecyl sulfate, and therefore the mobility, whereas proline may affect the conformation of the sodium dodecyl sulfate-protein complex. These effects may depend on the position of the substitution in the chain. Sodium dodecyl sulfate gel electrophoresis is thus able to detect neutral substitutions not usually visible in regular electrophoresis. © 1978.