Detection of Proteins and Nucleic Acids After Electrophoretic Separation

DETECTION OF PROTEINS AND NUCLEIC ACIDS AFTER ELECTROPHORETIC SEPARATION 

Following an electrophoretic run, the band from the tracking dye is often the only visible band. The detection of separated proteins and nucleic acids requires subsequent treatment of the separation pattern for visualization. This treatment may be performed directly on the gel, or may require a blotting step in which the entire separation pattern is transferred onto a thin membrane material. The choice of detection method depends on the concentrations of analytes in the separated zones and whether recovery of the purified sample is required. 

A silver stain has been introduced that is 100 times more sensitive for proteins than Coomassie Blue, and 4 times more sensitive for nucleic acids than ethidium bromide.14 This stain is based on the reduction of Ag+ by thiol, tyrosine and amine functional groups in proteins and by the purine bases in DNA. The solid silver formed by reduction precipitates in the gel forming a permanent stain in the protein-nucleic acid zones, and is not reduced by bulfer or gel materials, so that 

Coomassie Brilliant 590 General protein stain, 10 times 

Blue R-250 more sensitive than Amido Black 

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