The Gross Conformation of Protein-Sodium Dodecyl Sulfate Complexes

Abstract The interaction of sodium dodecyl sulfate with a wide variety of proteins is characterized by a high binding ratio when the monomer concentration of amphiphile exceeds 5 x 10-4 m. This binding ratio on a gram to gram basis is identical for all proteins investigated. The protein portion of the complex contains a high degree of order, and hydrodynamic studies suggest that the complex is a rodlike particle, the length of which varies uniquely with the molecular weight of the protein moiety. These results explain the empirical observation that proteins dissolved in aqueous solutions containing high concentrations of sodium dodecyl sulfate have electrophoretic mobilities on polyacrylamide gels which are a unique function of their molecular weights. In addition, the data suggest a possible model for the conformation of membrane proteins and their interactions with phospholipid.