Bioluminescent light is produced by release of energy during chemical reactions. Oxidation of luciferin occur which is light emitting compound. It is regulated by enzymes luciferase or photoprotein. Photoprotein are variants of luciferase which require factors like oxygen and luciferin for light emission. Photoproteins are triggers that bind calcium or magnesium ions to produce light which cause change in protein.
Light Producing Reactions
In oceans 4 luciferin genes are involve in bioluminescence which are highly conserved across phyla. Luciferase and photoproteins are derived from evolutionary lineage. Coelentrazine use as luciferin by cnidarians, photoprotein used by Hydrozoans, scyphozoans use luciferase. Coelentrazine is light emitter in nine phyla .sometime luciferin is taken through diet as it is also present in non-luminescence marine organisms.
Bacterial
Luminescent of bacteria involve the oxidation of luciferin with aldehyde long chain and 2 luciferase subunit.
Dinoflagellate
Tetrapyrrole is luciferin of Dinoflagellate similar to chlorophyll but interconverted on circadian basis. Its light emission is sensitive to pH. Change in pH cause structural change of luciferase exposing active site to luciferin. There are some luciferin binding proteins also present to which luciferin binding occur until pH drop. Circadian periodicity of luminescence can be imply by binding proteins. Dinoflagellate of luciferin was cloned from Lingulodinium polydrum.
Ostracod luciferin
Kato reveal that luciferin of ostracod synthesize from tryptophan, arginine and isoleucine found in Cyprinid ostracod and midshipman man fish. Its luciferase were cloned from Vargula Hilgendorf. Cypridind luciferin is consumed by some fishes whose light organ is extend to digestive tract.
Ceolenterazine
Two widely used luciferin in marine environment are imidazopyrazinons and cypridind luciferin present in coelenterazine.it was given its name for its presence in cnidarians Aequorea, Renilla and squid with some other organisms. Some light-emitting chemicals found naturally in squid and in firefly squid Watasemia in disuphide form. Luciferase and photoprotein occur naturally in conjunction with Ceolenterazine. Ceolenterazine in conjunction with photoprotein are used by Hydrozoans, ctenophore and radiolarians.
Light emission by luciferase instead of photoprotein use luciferin binding protein to control exposure of lucferin to oxidation .coelentrazine binding protein of sea pansy originate from R.reniforms and R.mulleri. It is confined within helicase of these proteins and escape through hole that open the calcium ion binding.
