Sodium dodecyl sulfate composites

Sodium dodecyl sulfate has been used to induce a dry, scaly skin condition in human subjects by daily treatment with a 4% aqueous solution on one leg over a period of 2 weeks. Measurements were made of stratum comeum hydration, scaliness, and lipid composition which were used to assess in vivo surfactant perturbations on desquamation [381]. 

The Diels-Alder reaction of methyl methacrylate with cyclopentadiene was studied [72] with solutions from three different regions of the pseudophase diagram for toluene, water and 2-propanol, in the absence and in the presence of surfactant [sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (HTAB)]. The composition of the three solutions (Table 6.11) corresponds to a W/O-fiE (A), a solution of small aggregates (B) and a normal ternary solution (C). The diastereoselectivity was practically constant in the absence and in the presence of surfactant a slight increase of endo adduct was observed in the C medium in the presence of surfactant. This suggests that the reaction probably occurs in the interphase and that the transition state has a similar environment in all three media. 

MEKC is a CE mode based on the partitioning of compounds between an aqueous and a micellar phase. This analytical technique combines CE as well as LC features and enables the separation of neutral compounds. The buffer solution consists of an aqueous solution containing micelles as a pseudo-stationary phase. The composition and nature of the pseudo-stationary phase can be adjusted but sodium dodecyl sulfate (SDS) remains the most widely used surfactant. 

A. Gerstner, Z. Csapo, M. Sasvari-Szekely, and A. Guttman, Ultrathin sodium dodecyl sulfate gel electrophoresis of proteins Effect of gel composition and temperature on the separation of sodium dodecyl sulfate-protein complexes, Electrophoresis, 21, 834 (2000). 

Various methods have been used to examine the composition of proteins adsorbed to SAMs. Overall adsorption patterns can be examined with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) [50, 76, 77]. Absorbed proteins are eluted from the surface with surfactant (SDS), and then separated by electrophoresis. The proteins of interest are examined by western blotting [50, 76, 77]. Protein-specific antibodies can be used to detect proteins of... 

The Langmuir-Blodgett method has been used to prepare hybrid films of an anionic Ru(ll) cyanide polypyridyl complex with LDHs [170]. An LDH film was formed on mica owing to the interaction between LDHs particles and the Ru(ll) cyanide polypyridyl complex that was pre-dispersed on the surface of mica. Water-in-oU emulsions composed of octane, water and sodium dodecyl sulfate (SDS) have been used to synthesize Mg/Al LDHs with carbonate as the interlayer anion [171] by constant pH or variable pH methods. A floccule or fiber-like LDH material that possesses similar chemical composition and properties to that synthesized using a conventional variable pH method was obtained. The resulting LDH shows high surface area and a narrow distribution of mesopores. 

Figure 6.2 represents the behavior of quasi-monodisperse double emulsions in (C , (pf) coordinates, where (pf is the initial volume fraction of droplets in the globules. Sorbitan monooleate (SMO) was used for the stabilization of the primary W/O emulsion and sodium dodecyl sulfate (SDS, CMC = 8 10 mol/1) was used for the stabilization of the oil globules in the external aqueous phase. Three different compositions zones, referred to as A, B, and C can be defined they differ by their qualitative behavior observed via microscopy. Moderate internal droplet volume fractions are considered first (cpf < 20%). If Ck = CMC/10, the system does not exhibit any structural evolution after a few days of storage (zone A). If C is... 

Most of the applications of HPLC for protein analysis deal with the storage proteins in cereals (wheat, corn, rice, oat, barley) and beans (pea, soybeans). HPLC has proved useful for cultivar identihcation, protein separation, and characterization to detect adulterations (illegal addition of common wheat flour to durum wheat flour) [107]. Recently Losso et al. [146] have reported a rapid method for rice prolamin separation by perfusion chromatography on a RP POROS RH/2 column (UV detection at 230nm), sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE), and molecular size determination by MALDl-MS. DuPont et al. [147] used a combination of RP-HPLC and SDS-PAGE to determine the composition of wheat flour proteins previously fractionated by sequential extraction. 

Subunit Composition of a Protein A protein has a molecular mass of 400 kDa when measured by gel filtration. When subjected to gel electrophoresis in the presence of sodium dodecyl sulfate (SDS), the protein gives three bands with molecular masses of 180, 160, and 60 kDa. When electrophoresis is carried out in the presence of SDS and dithiothreitol, three bands are again formed, this time with molecular masses of 160, 90, and 60 kDa. Determine the subunit composition of the protein. 

A predictive molecular thermodynamics approach is developed for microemulsions, to determine their structural and compositional characteristics [3.7]. The theory is built upon a molecular level model for the free energy change. For illustrative purposes, numerical calculations are performed for the system water, cyclohexane, sodium dodecyl sulfate as surfactant, pentanol as cosurfactant and NaCl as electrolyte. The droplet radius, the thickness of the surfactant layer at the interface, the number of molecules of various species in the droplets, and the distribution of the components between droplets and the continuous phase are calculated. The theory also predicts the transition from a mi-... 

Prehybridization/hybridization buffer 50% deionized formamide, 5 X SSC (standard saline citrate), 8 X Denhardt s solution, 50 mM sodium phosphate buffer (pH 6.5), 0.5% sodium dodecyl sulfate (SDS), 250 fig/ml denatured herring testes DNA, and 500 ng/ml yeast RNA (for the composition of SSC buffer and Denhardt s solution, see, e.g., Ausubel et al.13)... 

For large molecules of similar composition and sizes larger than the double layer, the mobilities are independent of the size, which makes their separation by electrophoresis difficult. Thus the migration velocity of polyelectrolytes like DNA molecules and proteins denatured with sodium dodecyl sulfate (SDS) is almost identical in pure electrolytes. Separations are attained only if their migration is modified by exclusion or sieving effects. 

Thanh and Shibasaki (10) proposed a trimeric structure for the 7S and a hexamerlc structure for the 9S dimer. Urea/sodium dodecyl sulfate polyacrylamide gel electrophoresis resolves the 7S globulin into six isomeric forms which are made up of three types of subunits (a, a and B) in varying proportions (10, 14, 15). The composition of the six isomeric proteins has been designated as follows B.., B, aB2> B, aa B B,, a B ... 

Subdivision below the monomer level occurs in the presence of sodium dodecyl sulfate and thiols (mercaptoethanol). The oxidase is thus identified as a multisubunit protein. Both yeast (57, 73) and Neitrospora crassa (74) oxidases were shown to be composed of seven subunits. Bovine heart oxidase, on the other hand, has been reported to have between two (75, 76) and six (57, 76) subunits. The subunits from yeast have molecular weights in the range of I, 40,000 II, 33,000 III, 22,000 IV, 14,000 V, 12,700 VI, 12,700 and VII, 4,600 (57, 77). The situation for bovine heart is less clear but the six subunits are reported to have molecular weights around I, 40,000 II, 25,000 III, 19,000 IV, 14,000 V, 10,000 and VI, 8,000 76). When fewer than six subunits are found, their molecular weights invariably correspond to some of the six reported 75-78). The subunit sizes differ for yeast and bovine heart (57). That the protein compositions differ is also reflected in the failure of antibodies against subunits II and VI of yeast oxidase to cross-react with bovine heart oxidase (75). 

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