Pore size gradient electrophoresis

Figure 3.27 Polyacrylamide gradient gel electrophoresis of human serum proteins. The proteins are separated in a gel which has an increasing concentration gradient with a parallel decrease in pore size, which restricts the movement of the larger molecules. Note the large number of different protein bands that can be demonstrated. (Photograph by permission of Dr D. Brocklehurst, Department of Clinical Chemistry, Doncaster Royal Infirmary, UK.)...

Lipoproteins can be analysed after separation by any of the methods described for their preparation. When only small quantities are available for analysis, however, electrophoresis is the general method of choice. Particularly useful is gradient gel electrophoresis which consists of the migration of charged particles through a polyacrylamide gel of increasing concentration. As the concentration of the gel increases, the pore size... 

CZE is a high resolution method provided that the sample is concentrated (>1 mg/ml) so that it can be loaded in a narrow zone. The buffer and pH for separation can be freely chosen, but buffer concentration should not exceed O.OIM to minimize Joule heating. In a homogeneous gel, separation occurs on the basis of both charge and size. In contrast, in a gradient polyacrylamide gel migration rates decrease until each protein species reaches its pore limit (15-17). This technique is termed "pore limit electrophoresis" and separates proteins on the basis of size. 

Electrophoresis Electrophoresis (also known as cataphoresis) is the transport of charged particles of colloidal size and bound contaminants due to the application of a low DC or voltage gradient relative to the stationary pore fluid. Compared with ionic migration and electroosmosis, mass transport by electrophoresis is negligible in low-permeabihty soil systems. However, mass transport by electrophoresis may become signiflcant in soil suspension systems, and it may also be a dominant transport mechanism for biocoUoids (i.e. bacteria) and micelles. 

---