Silver Staining of Glycoproteins and Polysaccharides

This procedure is not solely specific for carbohydrate side chains of proteins. Unglycosylated proteins may also be stained. To identify glycosylated proteins, the sample should be run in at least two identical lanes cut the gel and stain a lane with the common protein silver stain (Protocols 2.4.2.1 to 2.4.2.4) and the other lane by the described method. Compare pattern and intensity to identify glycoproteins. Glycosylated macromolecules are also stainable with Schiff s reagent (Protocol 2.4.4.1), but with less sensitivity. 

7% sodium metaperiodate (w/v) in Soln. A 1.4 ml of 25% ammonia and 4.0 ml 1 N NaOH are filled up to 16.0 ml with ddH2 0 then 4.0 ml 10% AgNOa (w/v) are added dropwise with shaking. The precipitate formed by a drop has to dissolve completely before giving the next. If the last drops are not dissolved completely, some ammonia can be added carefully. The resulting solution is pale brown. When the addition of silver is complete, ddH20 is filled up to 100 ml. 

The solution is prepared freshly before using. After use, the solution has to be destroyed by hydrochloric acid. 

All steps have to be done in glass vessels cleaned with concentrated nitric acid and rinsed thoroughly with de-ionized water. 

The gel is fixed after electrophoresis for at least 30 min, better overnight, in Soln. A. The fixing solution is poured off and the gel is agitated in Soln. B for 5 min. Wash the gel three times with ddH20 for 15 min each and transfer it in a new tray after the last wash. 

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