Electrophoretic procedures

The detection of abnormal hemoglobins In cord blood samples Is usually made with electrophoretic procedures. Four types of hemoglobin variants can be present, namely y-chaln variants, 3-chaln variants, and Hb-Bart s or yif Indicating some form of a-chaln deficiency or a-thalassemla. 

Nilsson CL et al. Identification of protein vaccine candidates from Helicobacter pylori using a preparative two-dimensional electrophoretic procedure and mass spectrometry. Anal Chem 2000 72 2148-2153. 

Brammer and Hemson employed an electrophoretic procedure to separate neomycin from blood-proteins before determining the neomycin concentration colorimetrically. 

Isozymes are also a common presence in enzyme preparations and they can often be detected via polyacrylamide gel electrophoresis. The detected presence of isozymes may result in the need for further purification steps and the kinetic characterization of each isozyme. It may be necessary to use nondenaturing electrophoretic procedures to separate the different isozymes. See Isozymes Enzyme Concentration... 

Electrophoretic Methods. Several electrophoretic procedures have been developed to fractionate or purify the various caseins (McKenzie 1971C Thompson 1971 Whitney 1977). Wake and Baldwin (1961) fractionated whole casein by zone electrophoresis on cellulose powder in 7 M urea and 0.02 ionic strength sodium phosphate buffer at pH 7 and 5°C. Payens and co-workers employed several somewhat different electrophoretic conditions for the fractionation and purification of the caseins on cellulose columns (Payens 1961 Schmidt and Payens 1963 Schmidt 1967). Three fractions, as-, k-, and /3-caseins, were separated at pH 7.5 and 30°C with 4.6 M urea-barbiturate buffer. The purification of asi-casein and the separation of the genetic variants of K-casein were accomplished by altering the electrophoretic conditions. Manson (1965) fractionated acid casein on a starch gel column stabilized by a density gradient at 25 °C. 

Although the size and shape of proteins can have some influence on solubility properties, the chief method of exploiting these properties is gel-filtration chromatography. In addition, preparative gel electrophoresis makes use of differences in molecular size. Proteins range in size from the smallest classified as proteins rather than polypeptides, around 5000 Da, up to macromolecular complexes of many million daltons. Many proteins in the bioactive state are oligomers of more than one polypeptide (see below), and these can be dissociated, though normally with loss of overall structure. Thus many proteins have two sizes that of the native state, and that (or those) of the polypeptides in the denatured and dissociated state. Gel-filtration procedures normally deal only with native proteins, whereas electrophoretic procedures commonly involve separation of dissociated and denatured polypeptides. 

The silver stained image used for matching can be taken from your file archive or from images available on the Internet, provided that identical electrophoretic procedures have been applied. The possibility of matching images derived from different 2D electrophoretic procedures has been investigated by Lemkin P. (92). 

Electrophoretic Separation. The net charge on a particular protein varies with the pH of the medium in which it is dissolved. Accordingly, application of an electric field to a buffered, heterogeneous protein solution often results in their differential migration in free solution or in heterogeneous systems with an inert supporting material, such as a polyacrylamide gel. Because of the difficulty of scaling up electrophoretic procedures, they are more commonly used for analytical applications than for the preparative scale purification of proteins. The use of electrophoresis is discussed in more detail in Experiment 4. 

The Cyt b-f complex contains the redox components Cyt /, Cyt 6-563 and the Rieske Fe-S protein, which in spinach have been identified as polypeptides of 33, 23 and 20 kDa respectively [95,98]. The spinach complex contains in addition a polypeptide of 17 kDa with no known redox function. The reported sizes of these polypeptides estimated by SDS-gel electrophoresis vary somewhat between different laboratories, presumably beca.use of slightly different electrophoretic procedures. The estimated size of the Cyt / polypeptide varies between different plants, even when analysed in the same electrophoresis system, although the gene sequences predict polypeptides of very similar relative molecular mass. 

In conclusion, CE is a valuable analytical tool that offers a number of possibilities for the analysis of a wide spectrum of forensicaUy interesting compounds. Practically all compounds which have been traditionally analyzed by GC, high-performance Uquid chromatography, thin-layer chromatography, or slab-gel electrophoresis, can be assayed by capillary electrophoretic procedures. AU methods of capillary electrophoresis can be validated and can meet the demands of good laboratory practice. 

Safer D (1989) An electrophoretic procedure for detecting proteins that bind actin monomers. InAnol. Biochem. 178 32-7... 

When HA samples contain only several disaccharide repeating units (from 10- to 12-mers), PAGE is not appropriate. An alternative gel electrophoretic procedure known as Fluorophore-Assisted Carbohydrate Electrophoresis (FACE) is more suited for these cases. In FACE technique, the sample is derivatized with a fluorescent group at the reducing end-group prior to electrophoresis. The FACE electrophoretic method was also described in detail by Cowman and Mendichi [270]. 

Using the electrophoretic procedure, the reference interval for bone ALP activity in healthy adults is 10 to 50U/L. Mean (SD) bone ALP concentrations, determined by immunoassays in healthy adults, were 13 tg/L. ... 

Analytical techniques that are used to measure therapeutic drugs includes immunoassay and instrumental techniques, such as chromatographic and electrophoretic procedures, and the so-called hyphenated techniques, where chromatographs are coupled with a mass spectrometer. ... 

JP Thornber, RPF Gregory, CA Smith and JL Bailey (1967) Studies on the nature of the chloroplast lamellae. I. Preparation and some properties of two chlorophyll-protein complexes. Biochemistry 6 391-395 JM Anderson, JC Waldron and SW Thorne (1978) Chlorophyll-protein complexes of spinach and barley thylakoids. Spectral characteristics of six complexes resolved by an improved electrophoretic procedure. FEES Lett 92 227-233... 

As in all electrophoretic procedures, a rigidly standardized technique is essential for consistent results. However, the variable absorption of the proteins in paper, and their different protein dye-binding capacities used for quantitation (see Section 6.5), necessitate several corrections which are both tedious and impractical. Such corrections are frequently ignored on the ground of simplicity. In the opinion of the writer, filter paper electrophoresis of serum albumin and globulins is an inaccurate separative procedure which is now outmoded. 

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