Light emission in the American firefly, Photinus pyralis, has been shown to involve the interaction of magnesium ion, oxygen, ATP, the enzyme luciferase, and the oxidizable substrate luciferin. Isoln from fireflies (yield from 15,000 active fireflies about 9 mg): Bitler, McElroy, Arch. Biochem. Biophys. 72, 358 (1957); from Japanese firefly (Luciola cruciata): Kishi et al., Tetrahedron Lett. 1968, 2847. Structure and synthesis: E. H. White et al., J. Am. Chem. Soc. 83, 2402 (1961); 85, 337 (1963); J. Org. Chem. 30, 2344 (1965); S. Seto et al., Bull. Chem. Soc. Jpn. 36, 331 (1963). Configuration: G. E. Blank et al., Biochem. Biophys. Res. Commun. 42, 583 (1971). Measurement of ATP: D. M. Karl, O. Holm-Hansen, Anal. Biochem. 75, 100 (1976). Review: L. J. Bowie, Methods Enzymol. 57, 15 (1978).