Chemiluminescence of firefly luciferin without enzyme.

We have been able to produce chemiluminescence in firefly luciferin without utilizing the enzyme luciferase. Following the analogous mechanism of the chemiluminescence of luminol in the organic solvent dimethyl sulfoxide, we have prepared synthetically the methyl ester of luciferin, the phosphate ester of luciferin and luciferyl adenylate by condensation in dimethyl sulfoxide with Khorana's reagent, dicyclohexylcarbodiimide and diazomethane, phosphoric acid, and adenylic acid respectively. These compounds in dimethyl sulfoxide in the presence of base emit a bright chemiluminescence. Like in vitro enzymatic bioluminescence, the luciferyl adenylate. chemiluminescence emission spectrum is dependent upon pH.