Cai Chuner, Wu Lian, Li Chunxia, He Peimin, Li Jie, Zhou Jiahai
Key Laboratory of Aquatic Genetic Resources and Aquaculture Ecology, Shanghai Ocean University, Shanghai 201306, People's Republic of China.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2011 May 1;67(Pt 5):579-83. doi: 10.1107/S1744309111007925. Epub 2011 Apr 27.
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.
条斑紫菜是中国最重要且广泛养殖的海藻之一。藻胆蛋白具有优异的光谱特性，在生物医学、食品、化妆品和化学合成染料行业中发挥着多种作用。在此，描述了从条斑紫菜中提取的两种藻胆蛋白——藻红蛋白和藻蓝蛋白的纯化及结晶过程。使用一种包括硫酸铵共沉淀和羟基磷灰石柱色谱的新方法，与先前报道的相比，这两种藻胆蛋白均实现了大规模生产，且质量和产量有所提高。天然聚丙烯酰胺凝胶电泳分析表明，藻红蛋白和藻蓝蛋白在溶液中以(αβ)(3)异源六聚体形式存在。藻红蛋白晶体的衍射分辨率达到2.07 Å，属于R3空间群。以六方轴表示的晶胞参数为a = b = 187.7，c = 59.7 Å，每个晶胞中有九个(αβ)(2)异源四聚体。藻蓝蛋白晶体在P2(1)空间群中的衍射分辨率为2.70 Å。马修斯系数分析表明，不对称单元中10 - 19个藻蓝蛋白(αβ)异源二聚体是合理的。自旋转函数计算澄清了这种不确定性，并表明不对称单元中组装有12个藻蓝蛋白(αβ)异源二聚体。
