Phycoerythrobilin is a red phycobilin, i.e. an open tetrapyrrole chromophore^[1] found in cyanobacteria and in the chloroplasts of red algae, glaucophytes and some cryptomonads. Phycoerythrobilin is present in the phycobiliprotein phycoerythrin, of which it is the terminal acceptor of energy. The amount of phycoerythrobilin in phycoerythrins varies a lot, depending on the considered organism. In some Rhodophytes and oceanic cyanobacteria, phycoerythrobilin is also present in the phycocyanin, then termed R-phycocyanin. Like all phycobilins, phycoerythrobilin is covalently linked to these phycobiliproteins by a thioether bond.

Phycoerythrobilin

Names
IUPAC name 3-[(2Z,5Z)-2-[[3-(2-carboxyethyl)-5-[[(2R)-4-ethenyl-3-methyl-5-oxo-1,2-dihydropyrrol-2-yl]methyl]-4-methyl-1H-pyrrol-2-yl]methylidene]-5-[[(3E,4R)-3-ethylidene-4-methyl-5-oxopyrrol-2-yl]methylidene]-4-methylpyrrol-3-yl]propanoic acid
Identifiers
CAS Number	18097-67-1 Y
3D model (JSmol)	Interactive image
ChemSpider	16741434 Y
MeSH	phycoerythrobilin
PubChem CID	20057005
InChI InChI=1S/C33H38N4O6/c1-7-20-19(6)32(42)37-27(20)14-25-18(5)23(10-12-31(40)41)29(35-25)15-28-22(9-11-30(38)39)17(4)24(34-28)13-26-16(3)21(8-2)33(43)36-26/h7-8,14-15,19,26,35H,2,9-13H2,1,3-6H3,(H,36,43)(H,37,42)(H,38,39)(H,40,41)/b20-7+,27-14-,28-15-/t19-,26-/m1/s1 N Key: IGJXAXFFKKRFKU-NDGVYKEISA-N N
SMILES C/C=C/1\[C@H](C(=O)N\C1=C/c2c(c(c([nH]2)/C=C\3/C(=C(C(=N3)C[C@@H]4C(=C(C(=O)N4)C=C)C)C)CCC(=O)O)CCC(=O)O)C)C
Properties
Chemical formula	C33H38N4O6
Molar mass	586.689 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references