Crystal Structure of Human Fibrinogen
Crystal Structure of Human Fibrinogen
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DOI：
10.1021/bi802205g
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发表时间：
2009-05-12
期刊：
影响因子：
2.9
通讯作者：
Doolittle, Russell F.
中科院分区：
文献类型：
--
作者：
Kollman, Justin M.;Pandi, Leela;Doolittle, Russell F.
人纤维蛋白原的晶体结构已确定为约 3.3 埃的分辨率。首先通过冷乙醇沉淀程序，然后通过 DEAE-纤维素上的逐步色谱法从人血浆中纯化蛋白质。获得在 SDS-聚丙烯酰胺凝胶上均质的产物。尽管如此，当数据收集后通过 SDS 凝胶电泳检查用于 X 射线衍射的单个晶体时，存在两种 α 链，表明在操作过程中发生了一些蛋白水解。 X 射线后晶体的氨基末端测序显示大部分完整的天然 α 链和 γ 链序列（天然 β 链被封闭）。其总体结构不同于来自鸡血的天然纤维蛋白原和报道的部分蛋白水解的牛纤维蛋白原，其卷曲螺旋区域的扭曲性质可能是由于独特的晶体堆积所施加的弱力所致。因此，该结构增加了溶液中可能出现的可能构象的库存。其他功能包括具有β链反平行排列的新颖界面以及来自相邻分子的卷曲线圈的独特切向关联。附着在 β 链上的碳水化合物基团异常突出，11 个糖残基全部被定位。与天然鸡纤维蛋白原的情况一样，没有可解析的电子密度与 α C 结构域相关。
A crystal structure of human fibrinogen has been determined at approximately 3.3 angstrom resolution. The protein was purified from human blood plasma, first by a cold ethanol precipitation procedure and then by stepwise chromatography on DEAE-cellulose. A product was obtained that was homogeneous on SDS-polyacrylamide gels. Nonetheless, when individual crystals used for X-ray diffraction were examined by SDS gel electrophoresis after data collection, two species of alpha chain were present, indicating that some proteolysis had occurred during the course of operations. Amino-terminal sequencing on post-X-ray crystals showed mostly intact native alpha- and gamma-chain sequences (the native beta chain is blocked). The overall structure differs from that of a native fibrinogen from chicken blood and those reported for a partially proteolyzed bovine fibrinogen in the nature of twist in the coiled-coil regions, likely due to weak forces imparted by unique crystal packing. As Such, the structure adds to the inventory of possible conformations that may occur In Solution. Other features include a novel interface with an antiparallel arrangement of beta chains and a unique tangential association of coiled coils from neighboring molecules. The carbohydrate groups attached to beta chains are unusually prominent, the full sweep of 11 sugar residues being positioned. As was the case for native chicken fibrinogen, no resolvable electron density could be associated with alpha C domains.