Cellulose acetate membrane electrophoresis (CAM-E)
Cellulose has a rather open, porous structure and a negative charge which, besides causing marked Electroendosmosis, can result in the binding of positively charged proteins. These properties of cellulose result in band spreading and consequent poor resolution of bands.
Cellulose acetate is a finer-grained derivative of cellulose made by the esterification of a proportion of the free -OH groups of cellulose to the acetate ester.
Cellulose acetate membranes give sharper protein bands and better resolution than paper, bind proteins less and have less endosmosis. As a result, CAM-E replaced paper electrophoresis and remained in use, mainly in medical diagnostic laboratories, for many years. The apparatus required for CAM-E is the same as for paper electrophoresis.
Cellulose acetate membranes are white and opaque but can be readily clarified and rendered transparent by immersion in “liquid paraffin”. The clear strips, with bands of stained protein, can be scanned to give an objective and quantitative assessment of the separation obtained (Fig). A more modern way of achieving the same end would be to capture a digital image of the CAM strip which could then be subjected to appropriate image analysis.
Figure of Densitometric scans of CAM-E results from different pathological sera.
References
Dennison, C. (2002). A guide to protein isolation . School of Molecular mid Cellular Biosciences, University of Natal . Kluwer Academic Publishers new york, Boston, Dordrecht, London, Moscow .
