Phycobilin
Phycobilins(fromGreek:φύκος(phykos)meaning "alga", and fromLatin:bilismeaning "bile" ) arelight-capturingbilinsfound incyanobacteriaand in thechloroplastsofred algae,glaucophytesand somecryptomonads(though not ingreen algaeandplants).[1]Most of their molecules consist of achromophorewhich makes them coloured.[1]They are unique among the photosynthetic pigments in that they are bonded to certain water-solubleproteins,known asphycobiliproteins.Phycobiliproteins then pass the light energy tochlorophyllsforphotosynthesis.[1]
The phycobilins are especially efficient at absorbing red, orange, yellow, and green light, wavelengths that are not well absorbed bychlorophylla.[2]Organisms growing in shallow waters tend to contain phycobilins that can capture yellow/red light,[3]while those at greater depth often contain more of the phycobilins that can capture green light, which is relatively more abundant there.
The phycobilinsfluoresceat a particular wavelength, and are, therefore, often used in research as chemical tags, e.g., by binding phycobiliproteins toantibodiesin a technique known asimmunofluorescence.[4]
Types[edit]
There are four types of phycobilins:[1]
- Phycoerythrobilin,which is red
- Phycourobilin,which is orange
- Phycoviolobilin(also known as phycobiliviolin) found inphycoerythrocyanin
- Phycocyanobilin(also known as phycobiliverdin), which is blue.
They can be found in different combinations attached to phycobiliproteins to confer specific spectroscopic properties.
Structural relation to other molecules[edit]
In chemical terms, phycobilins consist of an open chain of fourpyrrolerings (tetrapyrrole)[5]and are structurally similar to thebilepigmentbilirubin,[6]which explains the name. (Bilirubin's conformation is also affected by light, a fact used for thephototherapyofjaundicednewborns.)[7] Phycobilins are also closely related to the chromophores of the light-detecting plant pigmentphytochrome,[8]which also consist of an open chain of four pyrroles. Chlorophyllsare composed of four pyrroles as well, but there the pyrroles are arranged in a ring and contain a metal atom in the center of it.
References[edit]
- ^abcdFrank, H. A.; Cogdell, R. J. (2012-01-01), Egelman, Edward H. (ed.),"8.6 Light Capture in Photosynthesis",Comprehensive Biophysics,Amsterdam: Elsevier, pp. 94–114,doi:10.1016/b978-0-12-374920-8.00808-0,ISBN978-0-08-095718-0,retrieved2024-01-04
- ^González, A.; Sevilla, E.; Bes, M. T.; Peleato, M. L.; Fillat, M. F. (2016-01-01),"Chapter Five - Pivotal Role of Iron in the Regulation of Cyanobacterial Electron Transport",in Poole, Robert K. (ed.),Advances in Bacterial Electron Transport Systems and Their Regulation,Advances in Microbial Physiology, vol. 68, Academic Press, pp. 169–217,doi:10.1016/bs.ampbs.2016.02.005,PMID27134024,retrieved2024-01-04
- ^Crichton, Robert R. (2012-01-01), Crichton, Robert R. (ed.),"Chapter 10 - Magnesium–Phosphate Metabolism and Photoreceptors",Biological Inorganic Chemistry(Second ed.), Oxford: Elsevier, pp. 197–214,doi:10.1016/b978-0-444-53782-9.00010-3,ISBN978-0-444-53782-9,retrieved2024-01-04
- ^Mysliwa-Kurdziel, Beata; Solymosi, Katalin (2017)."Phycobilins and Phycobiliproteins Used in Food Industry and Medicine"(PDF).Mini-Reviews in Medicinal Chemistry.17(13): 1173–1193.doi:10.2174/1389557516666160912180155.PMID27633748.S2CID6563485.
- ^Stirbet, Alexandrina; Lazár, Dušan; Papageorgiou, George C.; Govindjee (2019-01-01), Mishra, A. K.; Tiwari, D. N.; Rai, A. N. (eds.),"Chapter 5 - Chlorophyll a Fluorescence in Cyanobacteria: Relation to Photosynthesis☆",Cyanobacteria,Academic Press, pp. 79–130,doi:10.1016/b978-0-12-814667-5.00005-2,ISBN978-0-12-814667-5,S2CID104302759,retrieved2024-01-04
- ^Sibiya, Thabani; Ghazi, Terisha; Chuturgoon, Anil (2022)."The Potential of Spirulina platensis to Ameliorate the Adverse Effects of Highly Active Antiretroviral Therapy (HAART)".Nutrients.14(15): 3076.doi:10.3390/nu14153076.ISSN2072-6643.PMC9332774.PMID35893930.
- ^Ennever, John F. (1988), Douglas, Ron H.; Moan, Johan; Dall’Acqua, F. (eds.),"Clinical and in Vitro Photochemistry of Bilirubin",Light in Biology and Medicine: Volume 1,Boston, MA: Springer US, pp. 143–151,doi:10.1007/978-1-4613-0709-9_19,ISBN978-1-4613-0709-9,retrieved2024-01-04
- ^Cornejo, Juan; et al. (1992)."Phytochrome Assembly: THE STRUCTURE AND BIOLOGICAL ACTIVITY OF 2(R),3(E)-PHYTOCHROMOBILINDERIVED FROM PHYCOBILIPROTEINS*".The Journal of Biological Chemistry.267(21): 14790–14798.doi:10.1016/S0021-9258(18)42109-6.PMID1634523.
- O'Carra P; Murphy RF; Killilea SD (May 1980)."The native forms of the phycobilin chromophores of algal biliproteins. A clarification".Biochem. J.187(2): 303–9.doi:10.1042/bj1870303.PMC1161794.PMID7396851.