Luciferin (from the Latin ''lucifer'', "light-bearer") is a generic term for the light-emitting compound found in organisms that generate

bioluminescence Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...

. Luciferins typically undergo an enzyme-catalyzed reaction with

molecular oxygen There are several known allotropes of oxygen. The most familiar is molecular oxygen (O2), present at significant levels in Earth's atmosphere and also known as dioxygen or triplet oxygen. Another is the highly reactive ozone (O3). Others are: *A ...

. The resulting transformation, which usually involves splitting off a molecular fragment, produces an

excited state In quantum mechanics, an excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum). Excitation refers to a ...

intermediate that emits light upon decaying to its

ground state The ground state of a quantum-mechanical system is its stationary state of lowest energy; the energy of the ground state is known as the zero-point energy of the system. An excited state is any state with energy greater than the ground state. ...

. The term may refer to molecules that are substrates for both

luciferase Luciferase is a generic term for the class of oxidative enzymes that produce bioluminescence, and is usually distinguished from a photoprotein. The name was first used by Raphaël Dubois who invented the words ''luciferin'' and ''luciferase'', ...

s and photoproteins.

Types

Luciferins are a class of small-molecule substrates that react with oxygen in the presence of a

(an enzyme) to release energy in the form of light. It is not known just how many types of luciferins there are, but some of the better-studied compounds are listed below. Because of the chemical diversity of luciferins, there is no clear unifying mechanism of action, except that all require molecular oxygen, The variety of luciferins and luciferases, their diverse reaction mechanisms and the scattered phylogenetic distribution indicate that many of them have arisen independently in the course of evolution.

Firefly

Firefly luciferin is the luciferin found in many Lampyridae species. It is the substrate of beetle luciferases ( EC 1.13.12.7) responsible for the characteristic yellow light emission from fireflies, though can cross-react to produce light with related enzymes from non-luminous species. The chemistry is unusual, as adenosine triphosphate (ATP) is required for light emission, in addition to molecular oxygen.

Snail

Latia luciferin is, in terms of chemistry, (''E'')-2-methyl-4-(2,6,6-trimethyl-1-cyclohex-1-yl)-1-buten-1-ol formate and is from the freshwater snail '' Latia neritoides''.EC 1.14.99.21
ORENZA: a database of ORphan ENZyme Activities, accessed 27 November 2009.

Bacterial

Bacterial luciferin is two-component system consisting of flavin mononucleotide and a fatty aldehyde found in bioluminescent bacteria.

Coelenterazine

Coelenterazine is found in radiolarians,

ctenophore Ctenophora (; ctenophore ; ) comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs"), and ...

cnidarian Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature is cnidocytes, specialized cells that th ...

squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...

, brittle stars,

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...

s, chaetognaths, fish, and shrimp. It is the prosthetic group in the protein aequorin responsible for the blue light emission.

Dinoflagellate

Dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...

luciferin is a

chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to a ...

derivative (i. e. a tetrapyrrole) and is found in some

dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...

s, which are often responsible for the phenomenon of nighttime glowing waves (historically this was called phosphorescence, but is a misleading term). A very similar type of luciferin is found in some types of euphausiid shrimp.

Vargulin

Vargulin Vargulin, also called Cypridinid luciferin, Cypridina luciferin, or Vargula luciferin, is the luciferin found in the ostracod ''Cypridina hilgendorfii'', also named ''Vargula hilgendorfii''. These bottom dwelling ostracods emit a light stream into ...

is found in certain ostracods and

deep-sea fish Deep-sea fish are fish that live in the darkness below the sunlit surface waters, that is below the epipelagic or photic zone of the sea. The lanternfish is, by far, the most common deep-sea fish. Other deep sea fishes include the flashlight ...

, to be specific, '' Poricthys''. Like the compound coelenterazine, it is an imidazopyrazinone and emits primarily blue light in the animals.

Fungi

Foxfire Foxfire, also called fairy fire and chimpanzee fire, is the bioluminescence created by some species of fungi present in decaying wood. The bluish-green glow is attributed to a luciferase, an oxidative enzyme, which emits light as it reacts with ...

is the bioluminescence created by some species of fungi present in decaying wood. While there may be multiple different luciferins within the kingdom of fungi, 3-hydroxy hispidin was determined to be the luciferin in the fruiting bodies of several species of fungi, including ''

Neonothopanus nambi ''Neonothopanus nambi'' is a poisonous and bioluminescent mushroom in the family Marasmiaceae. The genetic and molecular mechanisms underlying this species' bioluminescence were published in 2019, the first to be elucidated for a fungus. In 202 ...

'', '' Omphalotus olearius'', ''

Omphalotus nidiformis ''Omphalotus nidiformis'', or ghost fungus, is a gilled basidiomycete mushroom most notable for its bioluminescent properties. It is known to be found primarily in southern Australia and Tasmania, but was reported from India in 2012 and 2018. T ...

'', and ''

Panellus stipticus ''Panellus stipticus'', commonly known as the bitter oyster, the astringent panus, the luminescent panellus, or the stiptic fungus, is a species of fungus in the family Mycenaceae, and the type species of the genus '' Panellus''. A common and w ...

''.

Usage in science

Luciferin is widely used in science and medicine as a method of ''in vivo'' imaging, using living organisms to non-invasively detect images and in molecular imaging. The reaction between luciferin substrate paired with the receptor enzyme luciferase produces a catalytic reaction, generating bioluminescence. This reaction and the luminescence produced is useful for imaging such as detecting tumors from cancer or capable of measuring

gene expression Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, protein or non-coding RNA, and ultimately affect a phenotype, as the final effect. The ...

References

External links

* {{cite web , url = http://www.lifesci.ucsb.edu/~biolum/chem/detail1.html , title = Major luciferin types , date = 2009-01-09 , work = The Bioluminescence Web Page , publisher = University of California, Santa Barbara , access-date = 2009-03-06 Biological pigments Bioluminescence Fluorescent dyes Luciferins