Sodium dodecyl sulfate-polyacrylamide properties

The number of different proteins in a membrane varies from less than a dozen in the sarcoplasmic reticulum to over 100 in the plasma membrane. Most membrane proteins can be separated from one another using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), a technique that has revolutionized their study. In the absence of SDS, few membrane proteins would remain soluble during electrophoresis. Proteins are the major functional molecules of membranes and consist of enzymes, pumps and channels, structural components, antigens (eg, for histocompatibility), and receptors for various molecules. Because every membrane possesses a different complement of proteins, there is no such thing as a typical membrane structure. The enzymatic properties of several different membranes are shown in Table 41-2. 

One of the most widely used forms of gel electrophoresis is known as sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Polyacrylamide gel has several advantages that account for its extensive use. It has minimal adsorptive properties and produces a negligible electroosmotic effect (Hjelmeland and Chrambach 1981). In identity tests, for the determination of molecular weight, SDS-PAGE has been shown to be an appropriate, fast, and easy method that is often used in quality control laboratories. The use of SDS-PAGE followed by a densitometric analysis, such as MS, is a helpful technique for the determination of peptide or... 

A combination of circular dichroism, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, chemical crosslinking, and analytical ultracentrifugation studies showed that both the apo- and metallated derivatives of H21(31-mer) form two-stranded a-helical coiled coils in aqueous solution. Further characterization of these derivatives by EPR spin-label experiments helped to determine its three-dimensional backbone structure. In these studies, a Cys-21 mutant of the 31-mer coiled coil, H21/C21(31-mer), was prepared and labeled with a thiol-specific nltroxide spin label (MTSL = l-oxyl-2,2,5,5-tetramethyl-A -pyrroline-3-methyl-methanethiosulfonate) at position 21 of the peptide sequence which is the site of metal substitution in the ET heterodimer. Comparison of the low-temperature, dipolar-broadened spectrum of the spin-labeled dimer with those of magnetically dilute peptide samples yielded a backbone-to-backbone distance that was nearly identical to that of the GCN4 homodimer. Based on these results, computer modeling studies provided an estimate of the metal-to-metal distance in the ET heterodimer of m-m > 25 A. The electron-transfo properties of this system are now being studied by a combination of laser flash-quench and pulse radiolysis techniques. 

Wyckoff, M., Rodbard, D. and Chrambach, A. 1977. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate-containing buffer using multiphasic buffer systems Properties of the stack, valid Rf measurements, and optimized procedure. Anal Biochem. 78, 459-482. 

Slurrying, starch isolation, 674-676 Small-granule starches, centrifugation, 676 Smell chemicals, see Aroma compounds Smoke, interfacial properties, 609 (table) Sodium borohydride, 717 Sodium dodecyl sulfate, in SDS-PAGE. see Polyacrylamide gel electrophoresis Sodium thiosulfate, standardization, 519-520... 

A great variety of methods have been designed to extract acidic proteins from the chromosomes. They are all rather drastic, and it is not certain whether they allow the functional properties of the acidic proteins to survive the procedure. In one method designed in Bonner s laboratory [77] chromatin is prepared and then extracted with acid to exclude histones. After histone extraction, the residue is treated with sodium dodecyl sulfate. The DNA sediments and the proteins are collected in the supernatant. Ammonium sulfate precipitates the proteins, which can then be submitted to polyacrylamide gel electrophoresis. The polyacrylamide gel electrophoresis of such a preparation yields a multiband pattern. The patterns are similar for acid proteins extracted from rat kidney and liver, but different for acid protein extracted from pea bud chromatin and rat liver chromatin. 

---