Synthesis of Dehydroluciferin by Firefly Luciferase: Effect of Dehydroluciferin, Coenzyme A and Nucleoside Triphosphates on the Luminescent Reaction

The formation of dehydroluciferin (L) from luciferin (LH2) in the reaction catalyzed by firefly luciferase (EC 1.13.12.7) has been studied. The E·LH2-AMP complex may follow two different pathways: towards production of light and towards the synthesis of the E·L-AMP complex. This last step has an inhibitory effect on light emission as molecules of the enzyme are trapped in a light unproductive complex. The effects of CoA and nucleoside 5′-triphosphates (NTPs) on light emission are quantitatively different. CoA combines with the L moiety of the E·L-AMP complex, yielding L-CoA, promoting liberation of free luciferase, and increasing light yield. NTP reacts with the AMP moiety of the same complex, generating adenosine(5′)tetraphospho(5′)nucleoside (Ap4N) and, probably, the E·L complex and scarcely increasing light production. The results are discussed in relation to previous reports, by others, on luciferase.