The keto form of the firefly oxyluciferin
shows red chemiluminescence in solution and yellow-green bioluminescence in firefly luciferase.
Specifically, D-luciferin in the ATP was transformed into oxyluciferin
by luciferase whereby the light was generated.
In creatures that glow in the dark, luciferins react with oxygen and an enzyme that speeds everything up to produce oxyluciferin
, which is what actually emits the light.
This product, generally termed oxyluciferin
, subsequently relaxes to the ground state by photon emission.
ATP + D-Luciferin + [O.sub.2] [right arrow] Oxyluciferin
+ AMP + PPi + C[O.sub.2] + Light (560 nm).
Adenylation of luciferin by luciferase activates the substrate for conversion to oxyluciferin
and thus the resulting luminescence is proportional to ATP concentration (Manfredi et al., 2002; Lundin, 2014).
The luciferase present in the reagent uses luciferin, oxygen, and ATP as substrates in a reaction that produces oxyluciferin
and releases energy in the form of light.
FFL(Firefly luciferase) catalyzes the oxidation of luciferin in the presence of ATP, Mg2+ and molecular oxygen to produce light, oxyluciferin
, CO2 and AMP .
Through a sequence of another 2 reactions, the released pyrophosphate is converted into adenosine triphosphate (ATP), a cofactor for the enzyme luciferase, oxidizing luciferin to oxyluciferin
ATP also happens to be a key energy source in the enzymatic luciferase reaction, where the substrate luciferin is converted to oxyluciferin
plus emission of a photon.
The light-producing reaction requires molecular oxygen and ATP for the oxidation of luciferin to oxyluciferin
. The light produced is transmitted through tissue and detected by a sensitive charge-coupled device (CCD) camera; the acquired data can be presented as qualitative pseudocolor images or as quantitative photon counts.
ATP + D-luciferin + [O.sub.2] [light arrow] oxyluciferin
+ PPi + AMP + C02 + light.