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molecular weight markers for SDS-PAGE

arturo.galvani at itner.pharmacia.se arturo.galvani at itner.pharmacia.se
Thu Dec 21 03:17:15 EST 1995

     Eddie Diehl (diehl001 at mc.duke.edu) wrote:
     >I always used to run a lane of regular standards next to a prestained 
     >standard lane, then transfer, cut off the regular standards and stain 
     >with an amido black solution. I've always trusted the accuracy of 
     >their molecular weights much more than any manufacturer's prestained 
     I agree with Eddie, but there is another way to handle the problem of 
     markers for westerns.  If you run your gel with normal markers and 
     stain the blotted membrane (nitrocellulose, not PVDF, etc) with 
     Ponceau Red (available from many suppliers in ready-to-use form), then 
     you can destain the membrane with distilled water and easily visualise 
     the markers, and mark their position with a soft-leaded pencil.  Not 
     only this, but all your samples will also be stained, giving an 
     indication of how good protein transferral has been.  You then wash 
     out the Ponceau Red with PBS or TBS (comes off completely, and does 
     not affect probing), and proceed with blocking and probing the 
     membrane. I've always found this method to be extremely satisfactory.  
     Good luck,
     Arturo Galvani,
     Pharmacia, Nerviano, Milan Italy
     (all opinions expressed
     are strictly my own).

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