An enzyme that breaks down ATP and ADP into AMP and inorganic phosphate, effectively dismantling the cell’s energy currency. Found in plants, animals, and microbes, it regulates the levels of extracellular nucleotides that act as signaling molecules, calming the potent messages ATP broadcasts when released from damaged cells. In food science it has niche but interesting applications: potato apyrase has been studied for modifying starches and for analytical methods, and the enzyme’s ability to remove ATP underpins hygiene tests that detect microbial contamination by measuring the ATP microbes contain. Research into therapeutic uses explores calming excessive inflammatory signaling driven by extracellular ATP. Like many enzymes, its importance lies less in its fame than in its position at a busy metabolic intersection.