A specific stain for sulfhydryl groups in proteins after separation by polyacrylamide gel electrophoresis

A new method is described for specifically staining protein sulfhydryl groups after the proteins have been separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in slab gels. The stain will detect as little as 0.25 microgram of lysozyme and 1 microgram of most other proteins; the range of sensitivity for a specific protein depending on its sulfhydryl content. Proteins with no cysteine residues (type I collagen) and glycoproteins do not cause spurious staining.