Gel electrophoresis, analytical

Rodbard, D Chrambach, A, Estimation of Molecular Radius, Free Mobility, and Valence Using Polyacrylamide Gel Electrophoresis, Analytical Biochemistry 40, 95, 1971. 

Trudel, J. and Asselin, A. (1989) Detection of chitinase activity after polacrylamide gel electrophoresis. Analytical Biochemistry 178, 362-366. 

Rosenfeld, J., Capdevielle, J., Guillemot, J.C. and Ferrara, P. (1992) In-gel digestion of proteins for internal sequence analysis after one- or two-dimensional gel electrophoresis. Analytical Biochemistry 203, 173-179. 

Figure 6. Schematic diagram showing the replication mapping methodology. A platinum complex is added to DNA to form a cross-link and the site of platination is revealed by primer annealing, DNA polymerase chain extension, and gel electrophoresis analytical steps (see Ref. 96 for details).

The resulting oligonucleotide is often of surprising purity as judged by analytic HPLC or electrophoresis, and up to 30 mg of a deoxyeicosanucleotide (20-base DNA) can be routinely obtained. Nevertheless small amounts of short sequences, resulting from capping and from base-catalysed hydrolysis, must always be removed by quick gel filtration, repeated ethanol precipitation from water (desalting), reverse-phase HPLC, gel electrophoresis, and other standard methods. 

N,]S2-diaHyltartardiamide (DATD) [58477-85-3] (37). The cross-linking of polymerized monomer with the comonomer is what controls the pore size of the gel polymer mesh. This level of pore size control makes polyacrylamide gel electrophoresis an effective analytical tool. 

Typically, quantitative protein determination is done on the one hand by colorimetric or nephelometric methods, on the other hand for more difficult analytical problems by more sophisticated techniques such as high performance liquid chromatography (HPLC), gel-electrophoresis and immunoassay. However, these methods are tedious, time-consuming and expensive. 

Electrodriven Separation Techniques encompass a wide range of analytical procedures based on several distinct physical and chemical principles, usually acting together to perform the requh ed separation. Example of electrophoretic-based techniques includes capillary zone electrophoresis (CZE), capillary isotachophoresis (CITP), and capillary gel electrophoresis (CGE) (45-47). Some other electrodriven separation techniques are based not only on electrophoretic principles but rather on chromatographic principles as well. Examples of the latter are micellar... 

Classical gel electrophoresis has been used extensively for protein and nucleic acid purification and characterization [9, 10], but has not been used routinely for small molecule separations, other than for polypeptides. A comparison between TLC and electrophoresis reveals that while detection is usually accomplished off-line in both electrophoretic and TLC methods, the analyte remains localized in the TLC bed and the mobile phase is immediately removed subsequent to chromatographic development. In contrast, in gel electrophoresis, the gel matrix serves primarily as an anti-... 

The need to develop new materials for electrophoretic analysis and macromolecular separations prompted by the needs of the human genome project and the rapidly advancing fields associated with biotechnology, advances in the development of new analytical instrumentation—especially capillary electrophoresis, and practical limitations of the media currently used for gel electrophoresis [73]... 

Gersten, DM KimhaU, H Bijwaard, KE, Gel Electrophoresis in the Presence of Solnble, Aqneous Polymers Horizontal Sodinm dodecyl Snlfate-Polyacrylamdie Gels, Analytical Biochemistry 197, 59, 1991. 

Techniques for study of higher orders of protein stmcture include x-ray crystallography, NMR spectroscopy, analytical ultracentrifugation, gel filtration, and gel electrophoresis. 

A variety of formats and options for different types of applications are possible in CE, such as micellar electrokinetic chromatography (MEKC), isotachophoresis (ITP), and capillary gel electrophoresis (CGE). The main applications for CE concern biochemical applications, but CE can also be useful in pesticide methods. The main problem with CE for residue analysis of small molecules has been the low sensitivity of detection in the narrow capillary used in the separation. With the development of extended detection pathlengths and special optics, absorbance detection can give reasonably low detection limits in clean samples. However, complex samples can be very difficult to analyze using capillary electrophoresis/ultraviolet detection (CE/UV). CE with laser-induced fluorescence detection can provide an extraordinarily low LOQ, but the analytes must be fluorescent with excitation peaks at common laser wavelengths for this approach to work. Derivatization of the analytes with appropriate fluorescent labels may be possible, as is done in biochemical applications, but pesticide analysis has not been such an important application to utilize such an approach. 

SDS polyacrylamide gel electrophoresis (SDS-PAGE) represents the most commonly used analytical technique in the assessment of final product purity (Figure 7.1). This technique is well established and easy to perform. It provides high-resolution separation of polypeptides on the basis of their molecular mass. Bands containing as little as 100 ng of protein can be visualized by staining the gel with dyes such as Coomassie blue. Subsequent gel analysis by scanning laser densitometry allows quantitative determination of the protein content of each band (thus allowing quantification of protein impurities in the product). 

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