A luminescent ruthenium complex for ultrasensitive detection of proteins immobilized on membrane supports

SYPRO Ruby protein blot stain provides a sensitive, gentle, fluorescence-ba sed method for detecting proteins on nitrocellulose or polyvinylidene diflu oride (PVDF) membranes. SYPRO Ruby dye is a permanent stain composed of rut henium as part of an organic complex that interacts noncovalently with prot eins. Stained proteins can be excited by ultraviolet light of about 302 nm or with visible light of about 470 nm. Fluorescence emission of the dye is approximately 618 nm. The stain can be visualized using a wide range of exc itation sources utilized in image analysis systems including a UV-B transil luminator, 488-nm argon-ion laser, 532-nm yttrium-aluminum-garnet (YAG) las er, blue fluorescent light bulb, or blue light-emitting diode (LED). The de tection sensitivity of SYPRO Ruby protein blot stain (0.25-1 ng protein/mm( 2)) is superior to that of amido black, Coomassie blue, and india ink stain ing and nearly matches colloidal gold staining. SYPRO Ruby protein blot sta in visualizes proteins more rapidly than colloidal gold stain and the linea r dynamic range is more extensive. Unlike colloidal gold stain, SYPRO Ruby protein blot stain is fully compatible with subsequent biochemical applicat ions including colorimetric and chemiluminescent immunoblotting, Edman-base d sequencing and mass spectrometry. (C) 1999 Academic Press.