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 .

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