Bioluminescence

Light is produced by most bioluminescent organisms when a chemical called luciferin reacts with oxygen to produce light and oxyluciferin. The reaction between luciferin and oxygen is catalyzed by the enzyme luciferase. Luciferases, like luciferins, usually have different chemical structures in different organisms.

In addition to luciferin, oxygen, and luciferase, other molecules (called cofactors) must be present for the bioluminescent reaction to proceed. Cofactors are molecules required by an enzyme (in this case luciferase) to perform its catalytic function. Common cofactors required for bioluminescent reactions are calcium and ATP, a molecule used to store and release energy that is found in all organisms.

The terms luciferin and luciferase were first introduced in 1885. The German scientist Emil Du Bois-Reymond obtained two different extracts from bioluminescent clams and beetles. When Du Bois mixed these extracts they produced light. He also found that if one of these extracts was first heated, no light would be produced upon mixing. Heating the other extract had no effect on the reaction, so Reymond concluded that there were at least two components to the reaction. Reymond hypothesized that the heat-resistant chemical undergoes a chemical change during the reaction, and called this compound luciferin. The heat sensitive chemical, Reymond concluded, was an enzyme which he called luciferase.