title: Purification, crystallization and preliminary X-ray analysis of phycocyanin and phycoerythrin from Porphyra yezoensis Ueda.
abstract: Porphyra yezoensis is one of the most important and widely cultured seaweeds in China. Phycobiliproteins exhibit excellent spectroscopic properties and play versatile roles in the biomedical, food, cosmetics and chemical synthetic dye industries. Here, the purification and crystallization of phycoerythrin and phycocyanin, two phycobiliproteins extracted from P. yezoensis, are described. Using a novel protocol including co-precipitation with ammonium sulfate and hydroxyapatite column chromatography, both phycobiliproteins were produced on a large scale with improved quality and yield compared with those previously reported. Native PAGE analysis indicated that phycoerythrin and phycocyanin exist as (αβ)(3) heterohexamers in solution. The crystals of phycoerythrin diffracted to 2.07 Å resolution and belonged to space group R3. The unit-cell parameters referred to hexagonal axes are a = b = 187.7, c = 59.7 Å, with nine (αβ)(2) heterotetramers per unit cell. The crystals of phycocyanin diffracted to 2.70 Å resolution in space group P2(1). Matthews coefficient analysis shows that 10-19 (αβ) heterodimers of phycocyanin in the asymmetric unit would be reasonable. A self-rotation function calculation clarified this ambiguity and indicated that 12 (αβ) heterodimers of phycocyanin are assembled in the asymmetric unit.
authors.affiliation: Key Laboratory of Aquatic Genetic Resources and Aquaculture Ecology, Shanghai Ocean University, Shanghai 201306, People's Republic of China.
authors.forename: Chuner
authors.initials: C
authors.lastname: Cai
authors.forename: Lian
authors.initials: L
authors.lastname: Wu
authors.forename: Chunxia
authors.initials: C
authors.lastname: Li
authors.forename: Peimin
authors.initials: P
authors.lastname: He
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.forename: Jiahai
authors.initials: J
authors.lastname: Zhou
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D010798:Phycocyanin / Q000737:chemistry* / Q000302:isolation & purification; D010799:Phycoerythrin / Q000737:chemistry* / Q000302:isolation & purification; D044664:Porphyra / Q000737:chemistry*; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary
chemical_list: D010798:Phycocyanin; D010799:Phycoerythrin