title: Phycobilins of cryptophycean algae. Structures of novel bilins with acryloyl substituents from phycoerythrin 566.
abstract: Cryptomonad strain CBD phycoerythrin 566 carries four open-chain tetrapyrrole (bilin) prosthetic groups: three singly thioether-linked bilins at alpha-19, beta-82, and beta-158 and a bilin linked through two thioether bonds at beta-50,61 (amino acid sequence numbering from Wilbanks, S. M., Wedemayer, G.J., and Glazer, A.N. (1989) J. Biol. Chem. 264, 17860-17867). The structures of all four peptide-linked prosthetic groups were determined by 1H NMR spectroscopy. The bilin at beta-82 was identified as phycoerythrobilin (PEB), a common prosthetic group in cyanobacterial and red algal phycobiliproteins. The structures of the remaining bilins were novel. The bilin at alpha-19, designated Cys-bilin 618, differed from PEB in having additional double bonds between C-2 and C-3 of ring A and between C-12' and C-12", i.e. an acryloyl substituent at C-12 of ring C. The doubly linked bilin at beta-50,61 designated DiCys-bilin 584, differed from doubly linked PEB (Schoenleber, R.W., Lundell, D.J., Glazer, A.N., and Rapoport, H. (1984) J. Biol. Chem. 259, 5481-5484) in possessing an acryloyl substituent at C-12 of ring C in place of a propionyl substituent. Similarly, the bilin at beta-158, designated Cys-bilin 584, differed from singly-linked PEB in possessing an acryloyl substituent at C-12 of ring C in place of a propionyl substituent. The three novel cryptomonad bilins join heme d1 and chlorophylls c1, c2, and c3 as the only known porphyrin-derived natural products with acryloyl substituents.
authors.affiliation: Division of Biochemistry and Molecular Biology, Lawrence Berkeley Laboratory, University of California, Berkeley 94720.
authors.forename: G J
authors.initials: GJ
authors.lastname: Wedemayer
authors.forename: D E
authors.initials: DE
authors.lastname: Wemmer
authors.forename: A N
authors.initials: AN
authors.lastname: Glazer
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001654:Bile Pigments / Q000737:chemistry*; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D056890:Eukaryota / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D052980:Phycobilins; D010798:Phycocyanin / Q000737:chemistry*; D010799:Phycoerythrin / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry*; D013053:Spectrophotometry; D045725:Tetrapyrroles
chemical_list: D000596:Amino Acids; D001654:Bile Pigments; D052980:Phycobilins; D011758:Pyrroles; D045725:Tetrapyrroles; D010798:Phycocyanin; D010799:Phycoerythrin; C011069:phycocyanobilin