Chemical Reaction
The chemical reaction catalyzed by firefly luciferase takes place in two steps:
- luciferin + ATP → luciferyl adenylate + PPi
- luciferyl adenylate + O2 → oxyluciferin + AMP + light
Light is emitted because the reaction forms oxyluciferin in an electronically excited state. The reaction releases a photon of light as oxyluciferin returns to the ground state.
Luciferyl adenylate can additionally participate in a side reaction with O2 to form hydrogen peroxide and dehydroluciferyl-AMP. About 20% of the luciferyl adenylate intermediate is oxidized in this pathway.
The reaction catalyzed by bacterial luciferase is also an oxidative process:
- FMNH2 + O2 + RCHO → FMN + RCOOH + H2O + light
In the reaction, a reduced flavin mononucleotide oxidizes a long-chain aliphatic aldehyde to an aliphatic carboxylic acid. The reaction forms an excited hydroxyflavin intermediate, which is dehydrated to the product FMN to emit blue-green light.
Nearly all of the energy input into the reaction is transformed into light. The reaction is 80% to 90% efficient. As a comparison, the incandescent light bulb only converts about 10% of its energy into light. and a 150 lumen per Watt (lm/W) LED converts 20% of input energy to visible light.
Read more about this topic: Luciferase
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