Polyacrylamide gels interaction with

Size Isomers. In solution, hGH is a mixture of monomer, dimer, and higher molecular weight oligomers. Furthermore, there are aggregated forms of hGH found in both the pituitary and in the circulation (16,17). The dimeric forms of hGH have been the most carefully studied and there appear to be at least three distinct types of dimer a disulfide dimer connected through interchain disulfide bonds (8) a covalent or irreversible dimer that is detected on sodium dodecylsulfate- (SDS-)polyacrylamide gels (see Electroseparations, Electrophoresis) and is not a disulfide dimer (19,20) and a noncovalent dimer which is easily dissociated into monomeric hGH by treatment with agents that dismpt hydrophobic interactions in proteins (21). In addition, hGH forms a dimeric complex with ( 2). Scatchard analysis has revealed that two ions associate per hGH dimer in a cooperative... 

Amido black is a commonly used stain, but it is not very sensitive. It is often used to visualize concentrated proteins or components that are readily accessible to dyes such as proteins that have been transferred from a gel to nitrocellulose paper. Two of the more sensitive and more frequently used stains are Coomassie Brilliant Blue (R250 and G250) and silver stains. Because these stains interact differently with a variety of protein molecules, optimization of the fixative and staining solutions is necessary. The Coomassie stains are approximately five times more sensitive than amido black and are appropriate for both agarose and polyacrylamide gels. The silver stain is approximately 100 times more sensitive than Coomassie and is typically used for polyacrylamide gels. 

Chrambach, A Rodbard, D, Polyacrylamide Gel Electrophoresis, Science 172, 440, 1971. Chu, B Yeh, F Sokolov, EL Starodoubtsev, SG Khokhlov, AR, Interaction of Slightly Cross-linked Gels of Poly(diallyldimethylammonium chloride) with Surfactants, Macromolecules 28, 8447, 1995. 

Figure 5.11. Generic approaches to identify interacting proteins within complexes. The complex is isolated from cells by affinity purification using a tag sequence attached to a protein known to be in the complex. Alternatively, the complex can be immunprecipitated with an antibody to one of the proteins in the complex. The proteins are resolved by polyacrylamide gel electrophoresis, proteolyzed, and the mass of the resulting peptides is determined by mass spectrometry. Alternatively, the proteins can be proteolyzed and the resulting peptides resolved by liquid chromatography. The peptide masses are then determined by mass spectrometry and used for database searching to identify the component proteins.

Another approach has been to immobilize proteins within arrays of microfabricated polyacrylamide gel pads (Arenkov et al., 2000). Nanoliters of protein solutions are transferred to 100 x 100 x 20-pM gel pads and assayed with antibodies that are labeled with a fluorescent tag. Antigen imbedded in the gel pads can be detected with high sensitivity and specificity (Arenkov et al., 2000). Furthermore, enzymes such as alkaline phosphatase can be immobilized in the gel pads and enzymatic activity is readily detected upon the addition of an indicator substrate. The main advantage of the use of the threedimensional gel pad for fixation of proteins is the large capacity for immobilized molecules. In addition, the pads in the array are separated from one another by a hydrophobic surface. Thus, each pad behaves as a small test tube for assay of protein-protein interactions and enzymatic reactions (Arenkov et al., 2000). The disadvantage of the method is the need to microfabricate the array of gel pads in that microfabrication is... 

When labeled polypeptides traveling down the axon are analyzed by SDS polyacrylamide gel electrophoresis, materials traveling in the axon can be grouped into five distinct rate components [6], Each rate component is characterized by a unique set of polypeptides moving coherently down the axon (Fig. 28-3). As specific polypeptides associated with each rate class were identified, most were seen to move only within a single rate component. Moreover, proteins that have common functions or interact with each other tend to be moved together. These observations led to a new view of axonal transport, the structural hypothesis [7]. This model can be stated simply proteins and other molecules move down the axon as component parts of discrete subcellular structures rather than as individual molecules (Table 28-1). 

According to a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and CaM affinity chromatography analyses, compounds 44—53 interacted with both spinach and bovine-brain CaMs. In order to quantify the interaction of the phytotoxic agents 44—53 with... 

Western blotting has become an important, modern technique for analysis and characterization of proteins. The procedure consists of, first, the electrophoretic transfer (blotting) of proteins from polyacrylamide gels to synthetic membranes. The transferred blots are then probed using immunological detection methods to identify proteins of specific structure and/or function. In this experiment, bovine serum will be fractionated by SDS-PAGE and the proteins blotted onto a nitrocellulose membrane. Serum glycoproteins will be identified by their specific interaction with the lectin concanavalin A. 

Binding behavior of transition metal ions with polyallylamine20), poly(e-A-methacryloyl-L-lysine)2,), branched poly(ethyleneimine)s 22), water soluble polymer-bound iminodiacetic acid analogue 23), and polyacrylamide gel 241 has been reported. In these works, the effect of the polymer backbone has been discussed in terms of interaction of metal ions with the polymer chains. 

Zone electrophoresis is normally carried out horizontally in a suitable medium such as paper, polyacrylamide gel, starch gel or cellulose acetate. The sample components can be completely separated and quantitatively and qualitatively identified in much lower quantities than by the moving-boundary method. The procedure consists of saturating the support material with a buffer solution. The ends of the strip of support are immersed in separate reservoirs of buffer solution to maintain the saturation. The sample is then applied as a narrow band near one end of the support strip. A voltage potential is created down the length of the strip causing the sample components to ionize and then migrate at a rate dependent on their charge, molecular size and interactions with the support medium. When the process is complete, the strip is removed and developed for examination of the separated components. Densitometry is normally used for quantitation of the bands after suitable color development. 

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