CRYSTALLOGRAPHIC REFINEMENT AND ATOMIC MODELS OF THE INTACT IMMUNOGLOBULIN MOLECULE KOL AND ITS ANTIGEN-BINDING FRAGMENT AT 3.0-A AND 1.9-A RESOLUTION
CRYSTALLOGRAPHIC REFINEMENT AND ATOMIC MODELS OF THE INTACT IMMUNOGLOBULIN MOLECULE KOL AND ITS ANTIGEN-BINDING FRAGMENT AT 3.0-A AND 1.9-A RESOLUTION
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DOI：
10.1016/0022-2836(80)90252-1
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发表时间：
1980-01-01
影响因子：
5.6
通讯作者：
PALM, W
中科院分区：
文献类型：
--
作者：
MARQUART, M;DEISENHOFER, J;PALM, W
完整免疫球蛋白G1（λ）Kol及其Fab†片段的晶体结构分别在3.0 nm和1.9 nm分辨率下进行晶体学精修。所用的方法有真实的空间精化（RLSP）、能量和残差精化（EREF）、相位组合、约束刚体精化（CORELS）和差分及傅立叶变换检查。最终R值为0.24和0.26。这些分析允许分别在5 μ m和3 μ m分辨率下构建在先前分析中未详细看到的部件的原子模型（Colmanet al.，1976; Matsushimaet al.，1978年版）：即铰链片段、高变片段和它们与晶体学相关分子的铰链片段的紧密相互作用。铰链片段形成从Cys 527到Cys 530的短聚-L-脯氨酸双螺旋（Eu编号226到230）。前一段形成了一个开放的螺旋圈。该片段和聚-l-脯氨酸部分之后的片段，发现其在Fc片段晶体中是柔性的（Deisenhoferet等人，1976）可能允许抗体分子的臂和茎运动。将Kol的结合位点与Fab New的结合位点进行比较（Saulet al.，1978年）。Kol中高变环形成的狭窄裂缝充满了芳香族氨基酸侧链。在晶体中，高变环接触铰链和相关分子的相邻片段，伴随着可及表面积的大量损失。这种接触保存在Kol Fab晶体中，并可能发生在Kol冷沉淀物中。完整Kol和Fab New的四级结构的比较显示，除了肘角的大变化之外（Colmanet al.，1976年），横向域关联的变化。在从结合部位到远端的可能信号传输的上下文中讨论这些。尝试建立IgG 3铰链区段的模型，其相对于IgG 1是四重的（Michaelsenet al.，1977年），在科尔铰链结构的基础上。聚脯氨酸双螺旋似乎是最合理的模型。发现Fc部分在完整的Kol晶体中是无序的（Colmanet al.，1976年）。精细化进一步降低了晶体空间中的电子密度，Fc部分必须位于晶体空间中。无序，如果是静态的，在晶体状态下必须是四倍或更多.对Kol F（ab′）2的强度测量和它们与完整Kol晶体的比较提供了证据，表明无序主要是静态的性质.
The crystal structures of the intact immunoglobulin G1, (λ) Kol and its Fab†fragment were crystallographically refined at 3.0 Å and 1.9 Å resolution, respectively. The methods used were real space refinement (RLSP) energy and residual refinement (EREF), phase combination, constrained rigid body refinement (CORELS) and difference and Fourier map inspection. The finalR-values are 0.24 and 0.26. These analyses allowed the construction of atomic models of parts not seen in detail in the previous analyses at 5 Å and 3 Å resolution, respectively (Colmanet al., 1976; Matsushimaet al., 1978): i.e. the hinge segment, the hypervariable segments and their intimate interaction with the hinge segment of a crystallographically related molecule.The hinge segment forms a short poly-l-proline double helix from Cys527 to Cys530 (Eu numbering 226 to 230). The preceding segment forms an open turn of helix. This segment and the segment following the poly-l-proline part, which was found to be flexible in Fc fragment crystals (Deisenhoferet al., 1976) probably allow arm and stem movement of the antibody molecule. The combining site of Kol is compared with the combining site of Fab New (Saulet al., 1978). The narrow cleft formed by the hypervariable loops in Kol is filled with aromatic amino acid side-chains. In the crystal, the hypervariable loops contact the hinge and adjacent segments of a related molecule accompanied by a substantial loss in accessible surface area. This contact is preserved in Kol Fab crystals and presumably occurs in the Kol cryoprecipitate. A comparison of the quaternary structures of intact Kol and Fab New showed, in addition to the large change in elbow angle (Colmanet al., 1976), changes in lateral domain association. These are discussed in the context of a possible signal transmission from the combining site to the distal end. An attempt was made to model build the IgG3 hinge segment, which is quadruplicated with respect to IgG1 (Michaelsenet al., 1977), on the basis of the Kol hinge structure. A polyproline double helix appeared to be the most plausible model. The Fc part was found to be disordered in intact Kol crystals (Colmanet al., 1976). Refinement has reduced the electron density further in the crystal space, where the Fc parts must be located. Disorder, if static, must be fourfold or more in the crystalline state.Intensity measurements on Kol F(ab′)2and their comparison with intact Kol crystals provide evidence that the disorder is predominantly of a static nature.