Song Shuh Chyung, Xie Kefang, Czerwinski Marcin, Spitalnik Steven L, Wedekind Joseph E
Department of Pathology and Laboratory of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
Acta Crystallogr D Biol Crystallogr. 2004 Apr;60(Pt 4):788-91. doi: 10.1107/S0907444904002963. Epub 2004 Mar 23.
The NNA7 Fab fragment recognizes the human glycopeptide N blood-group antigen and has a high affinity for N-type glycophorin A (GPA). To provide insight into how antibodies recognize glycopeptide antigens, soluble Fab fragments were expressed in Escherichia coli, purified and crystallized using the hanging-drop vapor-diffusion method at 293 K. The best crystals were obtained from solutions of PEG monomethyl ether 5000 containing 4-8 mM yttrium chloride (YCl3). This rare-earth ion, which could be substituted with various lanthanides, changed the habit of crystals from multinucleated rods with a diffraction limit of 4.25 A resolution to a diamond-shaped morphology that grew as single crystals and diffracted X-rays to 1.75 A resolution. Data were collected that indicated that the crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 57.9, b = 77.1, c = 118.1 A and one Fab fragment per asymmetric unit. A molecular-replacement solution has been obtained and 86% of the molecule was fitted by use of an automated refinement procedure (ARP).
NNA7 Fab片段可识别人类糖肽N血型抗原，并且对N型血型糖蛋白A（GPA）具有高亲和力。为深入了解抗体如何识别糖肽抗原，可溶性Fab片段在大肠杆菌中表达，经纯化后于293 K采用悬滴气相扩散法进行结晶。最佳晶体是从含有4 - 8 mM氯化钇（YCl3）的聚乙二醇单甲醚5000溶液中获得的。这种稀土离子可用各种镧系元素替代，它将晶体习性从衍射极限为4.25 Å分辨率的多核棒状改变为菱形形态，该形态以单晶形式生长且X射线衍射分辨率达到1.75 Å。收集到的数据表明，晶体属于空间群P2(1)2(1)2(1)，晶胞参数a = 57.9、b = 77.1、c = 118.1 Å，每个不对称单元中有一个Fab片段。已获得分子置换解，并且使用自动优化程序（ARP）拟合了86%的分子。
