n. (Biochem.) a type of luciferin produced by the firefly Photinus pyralis. Its structure has been elucidated, and chemically it is recognized as 4, 5-Dihydro-2-(6-hydroxy-2-benzothiazol-2-yl)-4-thiazolecarboxylic acid, C11H8N3O2S2. It has found use in a very sensitive assay for ATP, in which concentrations of ATP as low as 10-11 molar can be detected. [ MI11 ] [ PJC ]