Visualization of proteins with a silver “stain”: A critical analysis

Abstract

Optimal silver staining of proteins in polyacrylamide gels is a fine balance between silver deposition on the proteins and the level of background staining. Reproduciable staining requires empirical standardization of many steps in the procedure. Silver staining in the present form does not stoichiometrically stain proteins, unlike Coomassie Blue. Staining intensity does not bear a linear relationship to protein mass. This is demonstrated by densitometric evaluation of both silver and Coomassie‐stained marker proteins fractioned by sodium dodecly1 sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). Although silver staining is more sensitive than Coomassie Blue, the increment in sensitivity is both different for individual proteins and dependent on protein concentration. Nevertheless it is an excellent method for one‐ and two‐dimensional (2‐D) electrophoresis if only minimal amounts of protein are available and only a qualitative or semi‐quantitative evaluation is required.