Jiang T, Zhang J, Liang D
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing.
Proteins. 1999 Feb 1;34(2):224-31.
The crystal structure of R-Phycoerythrin (R-PE) from Polysiphonia urceolata has been refined to a resolution of 1.9 A, based on the atomic coordinates of R-PE determined at 2.8 A resolution, through the use of difference Fourier method and steorochemistry parameters restrained refinement with model adjustment according to the electron density map. Crystallographic R-factor of the refined model is 0.195 (Rfree = 0.282) from 8-1.9 A. High resolution structure of R-PE showed precise interactions between the chromophores and protein residues, which explained the spectrum characteristic and function of chromophores. Four chiral atoms of phycourobilin (PUB) were identified as C(4)-S, C(16)-S, C(21)-S, and C(20)-R. In addition to the coupling distances of 19 A to 45 A between the chromophores which were observed and involved in the energy transfer pathway, high resolution structure of R-PE suggested other pathways of energy transfer, such as the ultrashort distance between alpha140a and beta155. It has been proposed that aromatic residues in linker proteins not only influence the conformation of chromophore, but may also bridge chromophores to improve the energy transfer efficiency.
基于在2.8 Å分辨率下测定的多管藻R-藻红蛋白（R-PE）的原子坐标，通过使用差值傅里叶法和根据电子密度图进行模型调整的立体化学参数约束精修，将多管藻R-藻红蛋白的晶体结构精修至1.9 Å分辨率。精修模型在8 - 1.9 Å范围内的晶体学R因子为0.195（Rfree = 0.282）。R-PE的高分辨率结构显示了发色团与蛋白质残基之间精确的相互作用，这解释了发色团的光谱特征和功能。藻尿胆素（PUB）的四个手性原子被确定为C(4)-S、C(16)-S、C(21)-S和C(20)-R。除了在能量转移途径中观察到的发色团之间19 Å至45 Å的耦合距离外，R-PE的高分辨率结构还表明了其他能量转移途径，例如alpha140a和beta155之间的超短距离。有人提出，连接蛋白中的芳香族残基不仅影响发色团的构象，还可能连接发色团以提高能量转移效率。
