Fluorescent labeling of proteins with Nile red and 2-methoxy-2,4-diphenyl-3(2H)-furanone: Physicochemical basis and application to the rapid staining of sodium dodecyl sulfate polyacrylamide gels and Western blots

The fluorescent hydrophobic dye Nile red allows the rapid, sensitive, and general staining of proteins in sodium dodecyl sulfate (SDS)-polyacrylamide gels. Nile red staining does no preclude further electroblotting of proein bands onto polyvinylidene difluoride (PVDF) membranes. The resulting Western blot can be stained with the covalent fluorescent dye 2-methoxy-2,4-diphenyl-3(2H)-furanone (MDPF) using a simple procedure. MDPF staining allows further N-terminal microsequencing and immunodetection of specific bands. This review considers the physicochemical, strucural, and analytical studies that have led to the development of Nile red and MDPF staining methods. The usefulness of these procedures is discussed in comparison to other currently available fluorescent and nonfluerescent protein detection methods.