Gel shift assays, or electrophoretic mobility shift assays (EMSA), provide a simple method to study DNA-protein interactions. Existing mobility shift assay protocols can be easily converted to infrared fluorescent assays by replacing the existing DNA oligonucleotides with IRDye® infrared dye end-labeled oligonucleotides. Binding and electrophoresis conditions are the same as any other EMSA detection method.