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

Reevaluation of the Electrophoretic Migration Behavior of Soluble Globular Proteins in the Native and Detergent-Denatured States in Polyacrylamide Gels

“…65 kDa), at least up to 15%T. Therefore, the reptation model (11) for electrophoretic migration of polymers does not apply, since this theory predicts a series of parallel curves for such plots (see below). Since some nonlinearity was observed for the larger proteins in the range of 5 to 15%T, running gels were extended to 20%T.…”

“…Subsequent structural analyses (6, 34) and physical measurements (11,35) have shown that SDS-protein complexes can form necklace-like structures, in which spherical micelles are distributed at regular intervals along unfolded polypeptide chains. Constant diameters of ϳ6.2 nm were observed for the micelles of most SDS-protein complexes in recent cryo-electron microscopy and small-angle X-ray-scattering studies (34).…”

“…On the grounds that detergent-protein complexes, as described in the necklace model, can be regarded as extended polymers, SDS-protein complexes, like nucleic acids, have been proposed (11) to migrate in a serpentine fashion designated as reptation (37,38), as suggested earlier (28). Since effective pore radii in polyacrylamide gels are typically around 3.0 nm, while the spacing between two neighboring micellar clusters in SDS-protein complexes was found to be Ͼ7.0 nm (34), the Ogston theory is not expected to be generally applicable (11).…”

The Supramolecular Association of Polyelectrolytes to Complementary Charged Surfactants and Protein Assemblies

“…Models for the association of polyelectrolytes to globular assemblies. a) flexible polyelectrolyte + surfactant micelle; [10,32] b) polyelectrolyte network + surfactant micelle; [10,32] c) polyampholyte + surfactant; [32,33] d) semirigid polyelectrolyte + surfactant; [10,42] e) semirigid polyelectrolyte (DNA) + macroion (hystone octamers). [57] stated, the rigidity of the polyelectrolyte interferes with the formation of spherical micelles, but the hydrophobic interaction of the aliphatic tails is preserved in a cylindrical symmetry.…”

“…[16] Micelle formation by surfactants in the presence of complementary charged gels and networks has also been experimentally and theoretically described. [32][33][34][35] In the theory of Khokhlov and co-workers [34] the cooperative collapse of a highly charged polyelectrolyte network upon addition of a surfactant was attributed to the reduction of the Donnan swelling due to the mobile ions (Figure 2 b).…”