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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; download the PMA Reference List. PMA dye is also available in H2O (40019), a convenient ready-to-use format.
Note: Scientists at Biotium have recently invented a new and improved dye for viability PCR, called PMAxx™ (40069). PMAxx™ functions in a manner very similar to PMA, but has much greater activity and ability to distinguish between live and dead bacteria. PMAxx™ can be used as a replacement for PMA in any bacterial viability-PCR assay. We recommend that customers interested in using PMA try PMAxx™ instead, for improved detection of viable bacteria.
For viability PCR of gram-negative bacteria we highly recommend using our new PMA Enhancer (31038) in conjunction with PMA. PMA Enhancer for Gram Negative Bacteria was designed to improve PMA-mediated discrimination between live and dead gram-negative bacteria. When a sequence from a gram-negative bacteria is amplified by PCR, samples pre-treated with Enhancer show a decrease in the signal from dead cells, with no change in the signal from live cells.
Biotium also provides strain-specific PMA Real-Time PCR Bacterial Viability kits with validated primers for selected pathogens: M. tuberculosis, S. aureus, MRSA, Salmonella, E. coli, E. coli O157:H7, Legionella and Listeria. These kits provide everything that you need for the selective detection of your favorite species of live bacteria by real-time PCR. Don’t see your favorite strain? Let us know at email@example.com.
For photoactivation of PMA, PMaxx™ or EMA dyes, we recommend the use of Biotium’s PMA-Lite™ LED Photolysis Device (E90002), which is designed to conduct photolysis under controlled conditions.
Molecular weight: 511
Abs = 464 nm (before photolysis)
Abs/Em = 510/610 nm (following photolysis and covalent attachment to DNA/RNA)
Dark red solid soluble in DMSO or DMF
Store at 4°C and protect from light at all times
Nocker, A., Cheung, C.Y., and Kamper, A.K. (2006). Comparison of propidium monoazide with ethidium monoazide for differentiation of live vs. dead bacteria by selective removal of DNA from dead cells. J. Microbio Meth. 67(2), 310-320.
Both PMA and PMAxx™ are both offered as 20 mM solutions in water. We also offer PMA as a solid, and customers often ask whether it needs to be dissolved in DMSO. While in some publications users have prepared their PMA stock solution in DMSO, this is not necessary. Unlike the older viability dye EMA, which is not soluble in water, PMA and PMAxx™ are very water soluble.
We have compared PMA and PMAxx™ for their ability to differentiate between live and dead cells in viability PCR assays, and in all bacteria strains tested*, PMAxx™ had better activity. Therefore, while we haven’t tested every bacterial strain, we recommend PMAxx™ for bacterial viability PCR.
A recent publication by Randazzo et al. compared several viability PCR dyes in norovirus, and found that PMAxx™ worked the best for that organism.
We have also compared PMA and PMAxx™ in viability PCR assays with the yeast Saccharomyces cerevisiae, and found that PMA was equal to or better than PMAxx™. Therefore we recommend PMA for yeast and fungus viability PCR.
Biotium offers the PMA-Lite™ LED Photolysis Device for light-induced cross-linking of PMAxx™ and PMA to dsDNA. The PMA-Lite™ is designed for samples in microcentrifuge tubes.
For users that have samples in a different format (for example, 96-well plates or filters), we will soon be releasing a new light box that will allow for greater flexibility of assay format.
Commercial halogen lamps (>600 W) for home use have been employed for photoactivating PMA in some publications, though results have not been consistent due to inevitable variation in the set-up configurations. If you decide to use a halogen lamp, we recommend that you lay tubes on a block of ice set 20 cm from the light source, on a rocking platform to ensure continuous mixing. Set the lamp so that the light source is pointing directly downward onto the samples (up to 45° downward slant is OK). Expose samples to light for 5-15 min.
Shipment Method: Shipping and handling methods will be assessed and calculated at time of shipment based upon item(s) storage temperature conditions.
Expedited shipment may be requested at time of checkout.
Please note that products with recommended storage at 4°C or -20°C may ship at ambient temperature. This will not affect product performance. When you receive the product, place it under the recommended storage conditions.