Chang W R, Jiang T, Wan Z L, Zhang J P, Yang Z X, Liang D C
National Laboratory of Biomacromolecules, Chinese Academy of Sciences, Beijing, China.
J Mol Biol. 1996 Oct 11;262(5):721-31. doi: 10.1006/jmbi.1996.0547.
The structure of R-phycoerythrin (R-PE) from Polysiphonia urceolata was determined at 2.8 A resolution. The crystals belong to space group R3 with unit cell dimensions of a = b = 189.8 A, c = 60.1 A. The subunit composition of R-PE is (alpha 2 beta 2)3 gamma. The three-dimensional structure of R-PE was solved by the multiple isomorphous replacement method. After several cycles of model building and refinement, the crystallographic R-factor of the final model is 18.0% with data from 10.0 to 2.8 A resolution. The four phycoerythrobilin chromophores alpha 84, alpha 140a, beta 84 and beta 155 in an (alpha beta) unit are each covalently bound to a cysteine residue through ring A. The phycourobilin chromophore is bound to cysteine beta 50 by ring A and bound to cysteine beta 61 by ring D. The ring A and ring D of phycourobilin deviate from the conjugate plane formed by ring B and ring C and the four rings form a boat-shaped structure. R-PE contains a 34 kDa gamma subunit that is assumed to lie in the central channel of the molecular disc (alpha 2 beta 2)3. The energy transfer and relationship between cysteine residues and chromophores are discussed.
在2.8埃分辨率下测定了来自多管藻的R-藻红蛋白（R-PE）的结构。晶体属于空间群R3，晶胞参数为a = b = 189.8埃，c = 60.1埃。R-PE的亚基组成为(α2β2)3γ。R-PE的三维结构通过多重同晶置换法解析。经过几个模型构建和精修循环后，最终模型在10.0至2.8埃分辨率数据下的晶体学R因子为18.0%。在一个(αβ)单元中的四个藻红胆素发色团α84、α140a、β84和β155各自通过A环共价结合到一个半胱氨酸残基上。藻尿胆素发色团通过A环与半胱氨酸β50结合，通过D环与半胱氨酸β61结合。藻尿胆素的A环和D环偏离由B环和C环形成的共轭平面，这四个环形成一个船形结构。R-PE包含一个34 kDa的γ亚基，假定位于分子盘(α2β2)3的中央通道中。讨论了能量转移以及半胱氨酸残基与发色团之间的关系。
