Vertical slab-gel apparatus

Figure 10.1 An illustration of a vertical slab-gel apparatus. Samples are applied in the wells set in the gel using a comb. Side-by-side comparison of samples is possible in slab systems (ref. 7). (Reprinted with permission from reference 7, Figure 11.2, Page 295, copyright (1994) Springer-Verlag.)...

Slab gels are now mote widely used than column gels. A slab gel on which several samples may be analyzed is more convenient to make and use than several individual column gels. Slab gels also offer the advantage that all samples are analyzed in a matrix, environment that is identical in composition. A typical vertical slab gel apparatus is shown in Figure 4.3. The polyacrylamide slab is prepared between two glass plates that are separated by... 

Electrophoresis apparatus for vertical slab gels and power supply Sample application buffer Tris, glycerol, bromophenol blue, pH 6.8 Protein solution buffer Tris, pH 6.8... 

The separation can be done in vertical or horizontal apparatus in rods or slabs. Because of the ease of use, horizontal slab electrophoresis systems are most commonly used in which the whole gel is submerged in buffer (Figure 13.8). 

A vertical electrophoresis apparatus for a slab gel. Courtesy of Hoefer Pharmacia Biotech, Inc., San Francisco. 

Fig. 33.1 Apparatus for vertical slab electrophoresis (components move downwards from wells, through the gel matrix).

Electrophoresis can be used to obtain a rapid separation of the proteins. A typical apparatus used for this purpose is shown in Figure 8.4. Proteins are first exposed to negatively charged sodium dodecyl sulfate, or SDS, which binds to the hydrophobic regions of the proteins, and causes them to unfold. The mixtures are placed into the wells on top of vertically placed gel slabs, as shown in Figure 8.4. Application of the electric potential, usually on the order of hundreds of volts, across the gel creates a force to move the protein molecules downward. Mobility of the proteins in the gel is given by... 

A typical gel electrophoresis apparatus is shown in Figure 11.23. The thin gel slab referred to above is contained between two glass plates. The slab is held in a vertical position and has notches at the top where the samples to be separated are spotted or streaked. In the configuration shown in the figure, only downward movement takes place, and thus only one type of ion, cation or anion, can be separated, since there is only one direction to go from the notch. 

Fig. 8.6, Apparatus for gel slab electrophoresis, a) Assembly of the cell. Two glass plates (P), 400 x 200 x 4 mm are kept at a suitable distance by two Perspex strips (S), 400 X 15 x 2 or 3 or 4 mm. The assembly is made leakproof with grease and kept together with 6 steel clips (C). It is pushed vertically into a trough (T) filled with plasticine, to close the lower end. It is filled with acrylamide solution to 3 cm from the top and a Perspex slot former (F) is introduced to 1 cm below the liquid level, b) Electrophoresis (transverse section). The lower end of the gel slab is in direct contact with the buffer of the lower reservoir, which contains the anode (A), a platinum wire about 20 cm long. The top of the gel is covered by about 2 cm of buffer, and forms electrical contact with the upper reservoir containing the cathode (K) through a paper wick (W) soaked with buffer.

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