C11H8N3O2S2

from The Collaborative International Dictionary of English v.0.48
Firefly luciferin \Fire"fly` lu*cif"er*in\, n. (Biochem.)
   a type of {luciferin} produced by the firefly {Photinus
   pyralis}.

   Note: 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]
    

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