Playing with Fire(flies)

Luciferin: The Sinfully Spectacular Secret to Bioluminescence

by Kelly Burchell-Reyes

While astrophysicists may extol the beauty of the skies, the most beautiful stars have fallen into our very biosphere and live among us as fireflies. These bringers of light are responsible for more than aesthetics! Fireflies use varying frequencies of light emissions as a means of passive defense and communication.

But what makes fireflies emit light, you ask? Keep your lab coats on!

Enter luciferin: the devilishly useful biomolecule which, with the help of the enzymatic protein luciferase, lights up the night sky. Luciferin exists as two enantiomers: L-Luciferin and D-Luciferin. L-Luciferin functions as a Coenzyme A, helping out with functions such as synthesizing fatty acids, extending drugs’ half-lives, and assisting the Citric Acid cycle in cellular respiration. D-Luciferin, however, is what reacts with Adenosine triphosphate (ATP), magnesium, and oxygen to emit light.

Photo courtesy of Terry Priest
Photo courtesy of Terry Priest

Now I know what you’re thinking: “We should take some Luciferin, and use it somewhere else!”

In fact, scientists are working to do just that. So far, D-Luciferin has been used research testing to locate tumours and monitor drug effectiveness within rodents without slicing the poor critters open.
Another useful application is creating glowing plants to line highways as a replacement for streetlights. Not only does this decrease the costs and energy associated with lamps, but it can also brighten the way for areas not currently lit up at night.

Furthermore, scientists are working on means of detecting harmful substances in water with bioluminescent bacteria.

If luciferin isn’t your favourite molecule yet, wavelengths can be varied to change the colour of the light emissions! Mutating the molecule’s sequence of amino acids, modifying the pH of the organism, and shifting between the keto-form and the enol-form of the molecule switch the hues between yellow-green and red.

Although Luciferin is cool as hell, please don’t ingest it. This molecule is an irritant to your mucous membranes and skin. Remember, always practice safe science!

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