Poljak R J, Amzel L M, Avey H P, Chen B L, Phizackerley R P, Saul F
Proc Natl Acad Sci U S A. 1973 Dec;70(12):3305-10. doi: 10.1073/pnas.70.12.3305.
The structure of the Fab' fragment of a human myeloma immunoglobulin was determined by x-ray crystallographic analysis at 2.8-A resolution. The Fourier map of the electron density was correlated with the aminoacid sequence to obtain a three-dimensional model. Four globular subunits, which correspond to the homology regions of the light and heavy chains, are arranged in a tetrahedral configuration. These subunits closely resemble each other, sharing a basic pattern of polypeptide chain folding. In each subunit, long sequences of tightly packed, hydrogen bonded polypeptide chain run parallel to the major axis of the subunit. No helical conformation can be seen. Different patterns of interchain disulfide linkage and unusual intrachain disulfide bonds that have been observed in other immunoglobulins can be explained with this model. The regions of hypervariable sequences in the light and heavy chains occur at one end of the molecule, in close spatial proximity.
通过X射线晶体学分析，以2.8埃的分辨率测定了人骨髓瘤免疫球蛋白Fab'片段的结构。将电子密度的傅里叶图与氨基酸序列相关联，以获得三维模型。四个球状亚基，对应于轻链和重链的同源区域，呈四面体构型排列。这些亚基彼此非常相似，共享多肽链折叠的基本模式。在每个亚基中，紧密堆积、形成氢键的多肽链的长序列与亚基的主轴平行。未见螺旋构象。该模型可以解释在其他免疫球蛋白中观察到的不同链间二硫键连接模式和不寻常的链内二硫键。轻链和重链中高变序列区域出现在分子的一端，空间距离很近。
