Phycobilins (from Greek: "polytonic|φύκος (phykos)" meaning "alga", and from
Latin: "bilis" meaning "bile") are chromophores (light-capturing molecules) found in cyanobacteriaand in the chloroplasts of red algae, glaucophytes and some cryptomonads (though not in green algaeand higher plants). They are unique among the photosynthetic pigments in that they are bonded to certain water-soluble proteins, known as phycobiliproteins. Phycobiliproteins then pass the light energy to chlorophylls for photosynthesis.
The phycobilins are especially efficient at absorbing red, orange, yellow and green light, wavelengths which are not well absorbed by chlorophyll "a". Organisms growing in shallow waters tend to contain phycobilins that can capture yellow/red light, while those at greater depth often contain more of the phycobilins that can capture green light, which is relatively more abundant there.
The phycobilins fluoresce at a particular wavelength, and are therefore often used in research as chemical tags, e.g. by binding phycobiliproteins to antibodies in a technique known as
There are four types of phycobilins:
Phycoerythrobilin, which is red
Phycourobilin, which is orange
Phycoviolobilin(also known as phycobiliviolin) found in phycoerythrocyanin
Phycocyanobilin(also known as phycobiliverdin), which is blue.
They can be found in different combinations attached to phycobiliproteins to confer specific spectroscopic properties.
tructural relation to other molecules
Chemically, phycobilins consist of an open chain of four
pyrrolerings (" tetrapyrrole") and are structurally similar to the bilepigment bilirubin, which explains the name. (Bilirubin's conformation is also affected by light, a fact used for the phototherapyof jaundiced newborns.)Phycobilins are also closely related to the chromophores of the light-detecting plant pigment phytochromewhich also consist of an open chain of four pyrroles. Chlorophylls are composed of four pyrroles as well, but there the pyrroles are arranged in a ring and contain a metal atom in the center.
* O'Carra P, Murphy RF, Killilea SD. "The native forms of the phycobilin chromophores of algal biliproteins. A clarification." Biochem J. 1980 May 1;187(2):303-9. PMID 7396851
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phycobilin — phy·co·bi·lin (fī kō bīʹlĭn) n. Any of a group of water soluble proteinaceous pigments that occur in red algae and cyanobacteria. [phyco + Latin bīlis, bile + in.] * * * … Universalium
phycobilin — noun any of a group of highly coloured pigments found in some photosynthetic algae; they are open chain tetrapyrroles related to mammalian bile pigments … Wiktionary
Phycobilin — Phy|co|bi|lin [↑ Phyco u. ↑ Bilin (1)]: in Blau u. Rotalgen vorkommende Tetrapyrrole, die – an Proteine zu Phycobiliproteinen (↑ Biliproteine) gebunden – als blaue (Phycocyanine) bzw. rote (Phycoerythrine) Photosynthesepigmente fungieren … Universal-Lexikon
phycobilin — phy·co·bi·lin .fī kō bī lən, bil ən n any of a class of pigments that occur in the cells of algae, are active in photosynthesis, and are proteins combined with pyrrole derivatives related to the bile pigments … Medical dictionary
phycobilin — phy·co·bilin … English syllables
phycobilin — noun water soluble proteinaceous pigments found in red algae and cyanobacteria • Hypernyms: ↑pigment … Useful english dictionary
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