Solubilization of oil-soluble dyes by sodium dodecyl sulfate-protein polypeptide complexes with reference to SDS-polyacrylamide gel electrophoresis.

Sodium dodecyl sulfate binds to the linear polypeptide derived from a protein to form micelle-like clusters (Takagi, T., Tsujii, K. and Shirahama, K. (1975) J. Biochem. 78, 939--947) which are expected to solubilize lipophilic materials. Such clusters were found to afford the complexes strong solubilizing power against oil-soluble dyes, comparable or slightly superior to SDS micelles, by conventional solubilizing technique (equilibration with solid dye) and by gel chromatography technique first applied to measure solubilization by such complexes. Solubilization behavior of the bound SDS was insensitive to the kind of protein polypeptide, in contrast to the variety found in the pioneering similar study on the complexes between SDS and initially native proteins (Steinhardt, J., Stocker, N., Carroll, D. and Birdi, K.S. (1977) Biochemistry 16, 718--725). The knowledge of the solubilizing power of SDS-protein polypeptide complexes seems to be valuable in design of experiments and interpretation of results obtained in application of SDS-polyacrylamide gel electrophoresis to samples containing lipophilic materials.