Bioluminescence
Bioluminescence is the phenomenon that takes place in a limited
number of organisms by which visible light is produced via a chemical
reaction within their system. It is basically a process in which
potential chemical energy is turned into electrical (luminous)
energy, without the usual accompaniment of intense heat. In other
words, it's really pretty cool, in more ways than one. Ha! Anyway,
it is predominantly a marine occurrence, with a few rare exceptions
seen in the forms of fireflies and glowing fungus, along with
several other terrestrial creatures.
The Bioluminescence Cycle
Cool animated gif courtesy of Bioluminescence Info Page.
The bioluminescence cycle involves three main events.
1) Luciferin, the substrate of the light producing reaction, is
subjected to an oxidation reaction with molecular O2, which the enzyme, luciferase, catalyzes.
2) As a result, light is given off, while the luciferin is converted
into a deactivated form, oxyluciferin.
3) In an effort to restore luciferin activity, chemical energy
in the form of ATP must be spent to transform oxyluciferin into
luciferin.
Since ATP is a key component of the bioluminescence cycle, there
have been developed assays to detect for ATP in biological tests
by using bacterial luciferase enzymes.
Also, a few other things should be noted regarding the luciferase
enzymes. First, although different luciferases are very diverse
in their structure as well as the specific reactions that they
enhance, they all oxidize their substrates to an excited product
and release light energy. (3) Additionally, the exact purpose for exhibiting bioluminescent
behavior is not known, but there is speculation that it generally
acts to attract potential symbiotic host organisms.
This way to Luciferase Structure & Active Site
I'm down with da TOC