PMA (propidium monoazide) is a high affinity photoreactive DNA binding dye invented by scientists at Biotium for viability PCR of bacteria and other organisms. The dye is weakly fluorescent by itself but becomes more fluorescent after binding to nucleic acids. It preferentially binds to dsDNA with high affinity. Upon photolysis, the dye covalently reacts with DNA, thus resulting in permanent DNA modification. The dye is cell membrane-impermeable, and thus can be selectively used to modify only exposed DNA from dead cells while leaving DNA from viable cells intact. This feature makes the dye highly useful in the selective detection of viable pathogenic cells by quantitative real-time PCR in the presence dead cells whose DNA has been PMA-modified and thus can not be amplified. Since Biotium first developed PMA dye, there have been numerous publications on the use of the dye in pathogenic bacterial detection related to food and water safety, medical diagnosis and biodefense. PMA dye is also available in solid form.
Molecular weight: 511
Abs = 464 nm (before photolysis)
Abs/Em = 510/610 nm (following photolysis and covalent attachment to DNA/RNA)
