Decreased protein staining after chemical crosslinking

Reaction of several proteins with the homobifunctional amino group-directed reagents dithiobissuccinimidyl propionate or methylmercaptobutyrimidate is shown to decrease the subsequent Coomassie blue or silver staining of these proteins after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The decreased dye response is not due to the proximity of the crosslinked proteins since the monomers generated after bisection of the crosslinkers with beta-mercaptoethanol show reduced staining. Quantitation of dye absorbance relative to protein content (assayed by radioactivity) indicates that the decreased staining effect is variable, depending on the particular stain, crosslinker, and protein.