Sidler W, Nutt H, Kumpf B, Frank G, Suter F, Brenzel A, Wehrmeyer W, Zuber H
Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule, Zürich.
Biol Chem Hoppe Seyler. 1990 Jul;371(7):537-47. doi: 10.1515/bchm3.1990.371.2.537.
The first complete amino-acid sequence of the cryptomonad phycobiliprotein phycocyanin-645 from Chroomonas sp. is presented. The alpha 1-subunit contains 70 amino-acid residues and the alpha 2-subunit 80 residues. In each of the alpha-subunits a green, 697-nm absorbing chromophore is covalently bound to Cys18. Both alpha-subunits contain a high number of charged residues. The phycocyanin-645 beta-subunit consists of 177 amino-acid residues. Two phycocyanobilin chromophores are singly bound to Cys beta 82 and Cys beta 158. A purple cryptoviolin-like chromophore is doubly bound to Cys beta 50 and Cys beta 61. Sequence comparisons revealed that the phycocyanin-645 beta-subunit is closely related to red algal phycoerythrin (73% identical amino-acid residues) and not so close to C-phycocyanin (55% identical amino-acid residues). The phycocyanin-645 alpha-subunits represent a special type of phycobiliprotein and a direct relationship to other phycobiliproteins or any light-harvesting polypeptide-pigment complexes could not be derived by sequence comparisons.
