Polypeptides, anionic detergents

W. L. Mattice, "Conformational Changes Accompanying the Interaction of Anionic Detergents with Cationic Polypeptides", presented at the Amer. Chem. Soc. Mtg., Philadelphia, Aug. 1984. 

Interaction of Anionic Detergents with Cationic Residues in Polypeptides... 

Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) is one of the most important separation techniques for proteins. The addition of an anionic detergent, SDS, to the sample causes denaturation of proteins. Detergent donates the negative charge to the protein, which is proportional to the polypeptide chain length. SDS specifically binds to proteins in a mass ratio of 1.4 1. In this type of separation, migration rate of proteins exclusively depends on their molecular masses and not on other factors, listed previously. Such a system allows for the separation of molecules... 

Sodium dodecyl sulfate (SDS) electrophoresis affords a separation only according to the molecular sizes. The anionic detergent SDS forms anionic micelles with the proteins and causes unfolding and stretching of the polypeptide chains [17]. AU these micelles are negatively charged the mobilities are only dependent on the molecule sizes. The treatment with SDS causes denaturation of proteins. In practice SDS electrophoresis is mostly combined with disc electrophoresis [18]. 

Capillary electro kinetic chromatography with micellar pseudophases of ionogenic detergents, anionic SDS, or cationic cetyltrimethylammonium bromide, is capable of resolving small proteins or polypeptides (Mr<6500) with minor differences in hydrophobicity resulting, e.g., from replacement of a single noniono-genic amino acid by other electroneutral amino acid residue. 

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