Mechanism of oxidative carbon dioxide production during Renilla reniformis bioluminescence.

The oxidation of luciferin catalyzed by sea pansy luciferase results in the emission of light. Molecular oxygen is required and carbon dioxide is produced. When the reaction occurs in the presence of H(2) (18)O, both of the oxygens of the carbon dioxide are labeled. One of the oxygens arises from the nonenzymic exchange of the ketone group of the substrate; the other oxygen is incorporated during the enzymic oxidation of the luciferin. When the reaction is carried out in the presence of (18)O(2), neither of the oxygens of the carbon dioxide is labeled. Thus the source of oxygen in the carbon dioxide is water. A mechanism for the oxidative reaction is proposed.