Abe Marina, Suzuki Ryo, Kojima Kenichi, Tachibana Masaru
Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan.
Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
IUCrJ. 2020 Jun 26;7(Pt 4):761-766. doi: 10.1107/S2052252520007393. eCollection 2020 Jul 1.
Knowledge of X-ray diffraction in macromolecular crystals is important for not only structural analysis of proteins but also diffraction physics. Dynamical diffraction provides evidence of perfect crystals. Until now, clear dynamical diffraction in protein crystals has only been observed in glucose isomerase crystals. We wondered whether there were other protein crystals with high quality that exhibit dynamical diffraction. Here we report the observation of dynamical diffraction in thin ferritin crystals by rocking-curve measurement and imaging techniques such as X-ray topography. It is generally known that in the case of thin crystals it is difficult to distinguish whether dynamical diffraction occurs from only rocking-curve profiles. Therefore, our results clarified that dynamical diffraction occurs in thin protein crystals because fringe contrasts similar to fringes were clearly observed in the X-ray topographic images. For macromolecular crystallography, it is hard to obtain large crystals because they are difficult to crystallize. For thin crystals, dynamical diffraction can be demonstrated by analysis of the equal-thickness fringes observed by X-ray topography.
了解大分子晶体中的X射线衍射不仅对蛋白质的结构分析很重要，对衍射物理学也很重要。动态衍射为完美晶体提供了证据。到目前为止，仅在葡萄糖异构酶晶体中观察到了蛋白质晶体中清晰的动态衍射。我们想知道是否还有其他高质量的蛋白质晶体表现出动态衍射。在此，我们报告通过摇摆曲线测量和诸如X射线形貌术等成像技术在薄铁蛋白晶体中观察到动态衍射。众所周知，对于薄晶体，仅从摇摆曲线轮廓很难区分是否发生了动态衍射。因此，我们的结果表明薄蛋白质晶体中发生了动态衍射，因为在X射线形貌图像中清楚地观察到了与条纹相似的条纹对比度。对于大分子晶体学而言，很难获得大晶体，因为它们难以结晶。对于薄晶体，可以通过分析X射线形貌术观察到的等厚条纹来证明动态衍射。
