Becker M, Stubbs M T, Huber R
Abteilung für Strukturforschung, Max-Planck-Institut für Biochemie, Martinsried, Germany.
Protein Sci. 1998 Mar;7(3):580-6. doi: 10.1002/pro.5560070306.
Phycoerythrin 545 from the cryptomonad alga, Rhodomonas lens, has been crystallized under a wide variety of conditions. Although this type of photosynthetic light-harvesting protein is water soluble, detergents were always required for crystallization. The crystals were typically poorly ordered, or ordered in only two dimensions. However, crystals that were well-ordered in three dimensions could be obtained under two different conditions. Both used polyethylene glycol as precipitant and the detergent lauryldimethylaminoxide, but the additives that were critical for obtaining well-ordered crystals were propionamide in one case and Cs+/Br- in the other. Crystals obtained in the presence of propionamide have the space group P2(1)2(1)2(1), with cell constants of a = 85.6 angstroms, b = 108.2 angstroms, and c = 131.0 angstroms, and contain two dimers [i.e., 2 x (alpha2beta2)] in the asymmetric unit. They show diffraction to at least 3.0 angstroms resolution. The crystals grown with Cs+/Br- are nearly isomorphous. Both types of crystals show intense, strongly polarized fluorescence, suggesting that energy transfer in the crystals is highly efficient. This should provide a basis for quantitative investigation of the role of exciton interactions in energy transfer in cryptomonad phycobiliproteins.
来自隐藻门藻类莱茵衣藻的藻红蛋白545已在多种条件下结晶。尽管这类光合捕光蛋白是水溶性的，但结晶过程始终需要洗涤剂。晶体通常排列不佳，或仅在二维上有序排列。然而，在两种不同条件下可以获得三维排列良好的晶体。两者都使用聚乙二醇作为沉淀剂和洗涤剂月桂基二甲基氧化胺，但获得排列良好晶体的关键添加剂在一种情况下是丙酰胺，在另一种情况下是Cs⁺/Br⁻。在丙酰胺存在下获得的晶体具有空间群P2(1)2(1)2(1)，晶胞常数a = 85.6埃，b = 108.2埃，c = 131.0埃，并且在不对称单元中包含两个二聚体[即2×(α2β2)]。它们的衍射分辨率至少为3.0埃。用Cs⁺/Br⁻生长的晶体几乎是同晶型的。两种类型的晶体都显示出强烈的、高度偏振的荧光，这表明晶体中的能量转移是高效的。这应该为定量研究激子相互作用在隐藻藻胆蛋白能量转移中的作用提供基础。
