SYPRO Orange fluorescent staining of protein gels

This method for staining protein gels uses a fluorescent dye, SYPRO Orange, which is very sensitive to protein (4-10 ng protein/band). SYPRO Orange cannot be visualized with the naked eye and thus a fluorescence scanner is required for detection of protein bands (the excitation maxima [Ex] are 300/472 nm and the emission maximum [Em] is 570 nm). SYPRO Red fluorescent protein stain uses the same binding principle as SYPRO Orange; hence, this protocol can also be used for SYPRO Red stain (Ex are 300/550 nm and Em is 630 nm). This staining method is mass-spectrometer-compatible.