Model system studies of staining procedures for lysine and arginine residues

Using polyacrylamide films containg poly-lysine, polyarginine and DNA as test models, a variety of reportedly specific staining procedures have been examine. Contrary to published observations, mixtures of fast green and eosin Y show no specific staining of either lysine or arginine. Both amino-acids bind eosin from the mixture more strongly than fast green. Arginine apparently has a greater affinity for this eosin than has lysine which contradicts previous reports that lysine will be stained by eosin arginine will stain with fast green, if proteins containing both amino-acids are stained with dye mixture. In films containing lysine and/or arginine picric acid is shown to bind specifically to the arginine. The picric acidarginine complex resists disruption in 0.004 M borate buffer which is a solvent used for subsequent staining of lysine residues with bromophenol blue. Picric acid may also be used as a hydrolysant and substitute for hydrocholoric acid in a Feulgen-like procedure which stains DNA to the same level as the classiclal hydrochloric acid based procedure while also staining arginine present.