GENERAL CHARACTERISTICS OF BIOLUMI- NESCENCE ASSAY OF INTRACELLULAR ATP Bioluminescence Assay for Cell Viability

ATP as an indicator of cell viability. Adenosine triphosphate (systematic name 9-β-D-ribofuranosyl adenine-5′-triphosphate or 9-β-D-ribofuranosyl-6-aminopurine-5′-triphosphate) − a nucleotide, an adenosine triphosphate ester that is a derivative of adenine and ribose (ATP) − is the main energy carrier in cells of all living organisms (mammals, microorganisms, plants, etc.) [1]. Cleavage of one or two phosphate groups that occurs during ATP hydrolysis is accompanied by the release of energy. In cells, ATP transfers energy to other molecules upon hydrolysis to its low-energy analogs (ADP and/or AMP), which, in turn, acquire energy by adding phosphate groups and transforming into ATP. Intracellular ATP content is the main indicator of cell viability. Upon cell death, ATP synthesis is the first to be arrested, while its hydrolysis can continue for some time, hence, the intracellular ATP content drops sharply to zero value. The ATP content in viable cells of microorganisms is quite high -it ranges from 500 to 10,000 µg per g of dry biomass Determination of ATP concentration using bioluminescence assay. There are various methods to determine ATP concentration: enzymatic methods with spectrophotometric detection, radioactive and chromatographic methods, and others. The bioluminescence ATP assay is the most sensitive, rapid, and selective. As far back as in the 1940s, it was shown that ATP is a required component in the reaction catalyzed by the firefly luciferase enzym