Coelenterazine
Coelenterazine is a luciferin, a molecule that emits light after reaction with oxygen, found in many aquatic organisms across eight phyla. It is the substrate of many luciferases such as Renilla reniformis luciferase, Gaussia luciferase, and photoproteins, including aequorin, and obelin. All these proteins catalyze the oxidation of this substance, a reaction catalogued EC 1.13.12.5.
History
Coelenterazine was simultaneously isolated and characterized by two groups studying the luminescent organisms sea pansy and the cnidarian Aequorea victoria, respectively. Both groups independently discovered that the same compound was used in both luminescent systems. The molecule was named after the now-obsolete phylum coelenterata. Likewise, the two main metabolites – coelenteramide and coelenteramine – were named after their respective functional groups. While coelenterazine was first discovered in Aequorea victoria, it was later shown that they do not synthesize coelenterazine, but obtain it through their diet, largely from crustaceans and copepods.Occurrence
Coelenterazine is widely found in marine organisms including:- radiolarians
- ctenophores
- cnidarians such as Aequorea victoria, Obelia geniculata and Renilla reniformis
- squid such as Watasenia scintillans and Vampyroteuthis infernalis
- shrimp such as Systellaspis debilis and Oplophorus gracilirostris
- copepods such as Pleuromamma xiphias, Gaussia princeps and Metridia lucens
- chaetognaths
- fish including some Neoscopelidae and Myctophidae
- echinoderms such as Amphiura filiformis
The compound is generally used by luciferases internal to the organism, but in the copepod Metridia longa the luciferase is secreted into extracellular space, an unusual property.