Ethidium monoazide, bromide (EMA)

A fluorescent nucleic acid stain with a photoaffinity label. The dye, after photolysis, binds covalently to nucleic acids. The dye has been used to footprint drug binding sites on DNA, to modify plasmid DNA and to determine hematopoietic cell phenotype, function and position in the cell cycle. A particularly useful application of the dye is to selectively and covalently label dead cells in the presence of live cells. Because ethidium monoazide bromide is relatively impermeant to live cells, it selectively labels DNA in dead cells in a mixed population of live and dead cells. Photolysis following the dye application renders the dead cell DNA covalently labelled with the dye. one can then wash and fix the cell preparation for analysis by microscopy, fluorescence plate reader or flow cytometry. The major advantage of this method is that researchers can avoid extensive manipulation of live pathogenic organisms. Ethidium monoazide bromide has been used to differentiate between viable and dead bacteria by 5'-nuclease PCR. Biotium also offers propidium monoazide iodide (PMA, catalogue numbers 40013 and 40019). PMA is less membrane permeant than EMA and therefore more selective for dead cell labelling for qPCR quantitation of viable bacteria. For photoactivation of PMA or EMA dye, we recommend the use of Biotium’s PMA-Lite LED Photolysis Device (E90002), which is designed to conduct photolysis under controlled conditions. • Ex (pH3) = 458 nm • Ex/ Em (after photocrosslinking to nucleic acid) = 510/600 nm • orange solid soluble in DMF, or ethanol • Store desiccated at 4oC or -20oC and protect from light, especially in solution • C21H18BrN5 • MW: 420 • [58880-05-0]