THE USE OF SILVER STAIN IN SODIUM DODECYL-SULFATE POLYACRYLAMIDE-GEL ELECTROPHORESIS OF IMMUNOPRECIPITATES OBTAINED BY CROSSED IMMUNOELECTROPHORESIS AND LIQUID PRECIPITATION

Ag staining was examined as a means for detecting antigenic polypeptides separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) after recovery from immunoprecipitates produced by crossed immunoelectrophoresis and liquid precipitation. Both precipitin procedures resulted in detection of the expected polypeptides with bovine serum albumin (BSA) and human transferrin as model antigens, as well as microheterogeneity of BSA: antigenic polypeptides were rarely detected with Coomassie Brilliant Blue staining of SDS-PAGE. The technique is advantageous over the use of radiolabeled antigens in being less expensive and time consuming and over antibody-blot procedures in detecting antigenic activity prior to the denaturing conditions of SDS-PAGE. Possible draw backs are the appearance of antibody polypeptide chains on the electrophorograms as well as other non-antigenic components when crude extracts of virally-infected cells are used as antigen.