Two-dimensional polyacrylamide gel electrophoresis and the Isodalt system

Recently Altland et al. [116] published a procedure in which polyacrylamide gel electrophoresis is used first followed by isoelectric focusing. Moreover isoelectric focusing in the second dimension is carried out in a gel containing a gradient of from 0 to 8 M urea perpendicular to the pH axis. 

Methods for the determination of molecular weights of native proteins by use of homogeneous systems [112a] The value of T is that presented by Ferguson [96aj. 

Very recently a new principle has been introduced into two-dimensional polyacrylamide gel electrophoresis after the separation in the rod like gel has been completed, the whole gel is subjected to a protein-modifying reaction, or to a specific protein clearing reaction (e.g., trypsinization, CNBr cleavage, etc.) and the resulting components are subjected to slab gel electrophoresis in the perpendicular direction 

At present two-dimensional polyacrylamide gel electrophoresis in one of the most advanced electrophoretic procedures the main obstacle with this method is a reliable interpretation of very complex electrophoretograms containing several hundreds of zones. The procedures for computer evaluation of such maps are available from more specialized literature [117]. Another problem is that the first-dimension run (rod gel) must be done with much less material than the amount required for optimum detection in the slab gel step. With Coomassie Blue staining (and related methods) this is bypassed by overloading the rod gel at the expense of poorer resolution. More sensitive detection methods seem to be the solution here (Fig. 5.15) [118]. 

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