phycoerythrin
American Heritage Dictionary:
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phy·co·er·y·thrin
(fī'kō-ĕr'ĭ-thrĭn) 
n.
A red phycobilin occurring especially in the cells of red algae.
n.
A red phycobilin occurring especially in the cells of red algae.
Oxford Dictionary of Biochemistry:
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phycoerythrin
a red phycobilin; see phycobiliprotein.
| phycocyanobilin, phycocyanin, phycobilisome | |
| phycoerythrobilin, phycofluor, phycotoxin |
Wikipedia on Answers.com:
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Phycoerythrin
| Identifiers | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Symbol | Phycoerythr_ab | ||||||||
| Pfam | PF02972 | ||||||||
| InterPro | IPR004228 | ||||||||
| SCOP | 1qgw | ||||||||
| SUPERFAMILY | 1qgw | ||||||||
|
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Phycoerythrin is a red protein from the light-harvesting phycobiliprotein family, present in cyanobacteria, red algae and cryptomonads.[1]
Like all phycobiliproteins, phycoerythrin is composed of a protein part, organised in a hexameric structure of alpha and beta chains, covalently binding chromophores called phycobilins. In the phycoerythrin family, the phycobilins are: phycoerythrobilin, the typical phycoerythrin acceptor chromophore, and sometimes phycourobilin (marine organisms). Phycoerythrins are the phycobiliproteins that bind the highest number of phycobilins (up to six per alpha-beta subunit dimer).
Absorption peaks in the visible light spectrum are at 495 and 545/566 nm, depending on the chromophores bound and the considered organism. A strong emission peak exists at 575 ± 10 nm. (i.e., phycoerythrin absorbs slightly blue-green/yellowish light and emits slightly orange-yellow light.)
Phycoerythrin is an accessory pigment to the main chlorophyll pigments responsible for photosynthesis. The light energy is captured by phycoerythrin and is then passed on to the reaction centre chlorophyll pair, most of the time via the phycobiliproteins phycocyanin and allophycocyanin.
R-Phycoerythrin, or PE, is useful in the laboratory as a fluorescence-based indicator for the presence of cyanobacteria and for labeling antibodies in a technique called immunofluorescence, among other applications. There are also other types of phycoerythrins, such as B-Phycoerythrin, which has slightly different spectral properties. B-Phycoerythrin absorbs strongly at about 545 nm (slightly yellowish green) and emits strongly at 572 nm (yellow) instead and could be better suited for some instruments. B-Phycoerythrin may also be less "sticky" than R-Phycoerythrin and contributes less to background signal due to non-specific binding in certain applications.
R-Phycoerythrin and B-Phycoerythrin are among the brightest fluorescent dyes ever identified.
References
- ^ Glazer, A.N., 1989. Light guides. Directional energy transfer in a photosynthetic antenna. J. Biol. Chem. 264:1-4
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American Heritage Dictionary
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
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Oxford Dictionary of Biochemistry
Oxford University Press. Oxford Dictionary of Biochemistry and Molecular Biology © 1997, 2000, 2006 All rights reserved.
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