Luciferase - Chemical Reaction

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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