Differences in crystal properties and ligand affinities of an antifluorescyl Fab (4-4-20) in two solvent systems.
Differences in crystal properties and ligand affinities of an antifluorescyl Fab (4-4-20) in two solvent systems.
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抗荧光基 Fab (4-4-20) 在两种溶剂系统中的晶体性质和配体亲和力的差异。
DOI：
10.1002/prot.340030304
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发表时间：
1988
期刊：
影响因子：
2.9
通讯作者：
Edmundson,AB
中科院分区：
文献类型：
--
作者：
Gibson,AL;Herron,JN;He,XM;Patrick,VA;Mason,ML;Lin,JN;Kranz,DM;VossJr,EW;Edmundson,AB
将来自对荧光素具有高亲和力的鼠单克隆抗体（4 - 4 - 20）的抗原结合片段（Fab）与配体在聚乙二醇（PEG）和2-甲基-2，4-戊二醇（MPD）中以适合X射线分析的形式共结晶。在MPD中，完整抗体对荧光素的亲和力比在水性缓冲液中获得的值（3.4 × 1010 M −1）低300倍。当在结晶试验期间将MPD加入到配体化Feb的溶液中时，结合的荧光素的部分释放表明了这种降低的亲和力。在PEG中，配体保持与蛋白质牢固结合。在PEG中，Fe 2+配体属于单斜晶系，空间群为P21，a = 58.6，b = 97.2，c = 44.5 °，β = 95.2°。MPD空间群为三斜P1，a = 58.3，b = 43.4，c = 42.3 °，α = 83.9°，β = 87.6°，γ = 84.5°。收集两种形式的X射线衍射数据，分辨率为2.5 μ m。令人惊讶的是，配体抗荧光素Feb的三斜晶型具有与具有抗单链DNA活性的未配体Fab（BV 04 - 01）相同的空间群、非常相似的细胞尺寸和几乎相同的晶胞取向。
An antigen‐binding fragment (Fab) from a murine monoclonal antibody (4‐4‐20) with high affinity for fluorescein was cocrystallized with ligand in polyethylene glycol (PEG) and 2‐methl‐2,4‐pentanediol (MPD) in forms suitable for X‐ray analyses. In MPD the affinity of the intact antibody for fluorescein was 300 times lower than the value (3.4 × 1010M−1) obtained in aqueous buffers. This decreased affinity was manifested by the partial release of bound fluorescein when MPD was added to solutions of liganded Feb during crystallization trials, In PEG, the ligand remained firmly bound to the protein. The liganded Feb crystallized in the monoclinic space groupP21in PEG, witha= 58.6,b= 97.2,c= 44.5 Å and β = 95.2°. In MPD the space group was triclinicP1, witha= 58.3,b= 43.4,c= 42.3 Å, α = 83.9°, β = 87.6°, and γ = 84.5°. X‐ray diffraction data were collected for both forms to 2.5‐Å resolution. Surprisingly, the triclinic form of the liganed antifluorescyl Feb had the same space group, closely similar cell dimensions, and practically the same orientation in the unit cell as an unliganded Fab (BV04‐01) with activity against single‐stranded DNA.