The structure and thermodynamics of protein—SDS complexes in solution and the mechanism of their transports in gel electrophoresis process

Abstract A unified exposition of the structure, thermodynamics and transport of complexes formed by association of a surfactant sodium dodecyl sulfate (SDS) with water-soluble globular proteins in solution is presented. From small angle neutron scattering experiments we have determined the structure of the complex to be a polymer-like object consisting of a string of SDS micelles decorating the hydrophobic patches of the unfolded polypeptide chain in solution. Based on this structural model we have predicted and observed a polymer-like phase separation of the denatured protein solution at suitable pH. This model can also successfully predict the mobility of the complexes in polyacrylamide gel during an electrophoresis process, if we adapt the well known reptation concept of diffusion of a single chain of polymer in gels.

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