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How does the photoprotein aequorin produce light in the jellyfish Aequorea?

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time-lapse photo of fireflies — Bioluminescence Time-lapse image of fireflies in the Catskill Mountains, New York. Firefly light is a cold light, with approximately 100 percent of the energy given off as light and only a minute amount as heat. Only light in the visible spectrum is emitted.

In the jellyfish Aequorea, the photoprotein aequorin produces light through a specific biochemical trigger rather than a traditional enzyme-catalyzed reaction.

Unlike systems that rely on the oxidation of luciferin via a catalyst, aequorin functions as a pre-charged complex. Luminescence occurs when the protein binds with calcium or strontium ions. This interaction causes the protein to undergo a structural change that results in the emission of light, a process that is essential to the bioluminescence observed in these organisms.12