Demonstration of proteins in electrophoresis gels using radioactive stains

We describe the use of 35S‐labelled stains for the detection of submicrogram amounts of protein in SDS polyacrylamide gels. Many stains used to detect protein can be rendered radioactive, and proteins can be detected by radiofluorography due to stain binding in the absence of visible color. Of the stains tested. [35S]Ponceau Red S and [35S]Serva Blue R gave the best results. The potential utility of protein detection with radioactive stains is discussed.