Protein and Organic-Molecular Crystallography With 300kV Electrons on a Direct Electron Detector

Kiyofumi Takaba; Saori Maki-Yonekura; Satoru Inoue; Tatsuo Hasegawa; Koji Yonekura

doi:10.3389/fmolb.2020.612226

Protein and Organic-Molecular Crystallography With 300kV Electrons on a Direct Electron Detector

Front Mol Biosci. 2021 Jan 6:7:612226. doi: 10.3389/fmolb.2020.612226. eCollection 2020.

Authors

Kiyofumi Takaba¹, Saori Maki-Yonekura¹, Satoru Inoue², Tatsuo Hasegawa², Koji Yonekura^{1

3

4}

Affiliations

¹ Biostructural Mechanism Laboratory, RIKEN SPring-8 Center, Sayo, Japan.
² Department of Applied Physics, The University of Tokyo, Tokyo, Japan.
³ Advanced Electron Microscope Development Unit, RIKEN-JEOL Collaboration Center, RIKEN Baton Zone Program, Sayo, Japan.
⁴ Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan.

Abstract

Electron 3D crystallography can reveal the atomic structure from undersized crystals of various samples owing to the strong scattering power of electrons. Here, a direct electron detector DE64 was tested for small and thin crystals of protein and an organic molecule using a JEOL CRYO ARM 300 electron microscope. The microscope is equipped with a cold-field emission gun operated at an accelerating voltage of 300 kV, quad condenser lenses for parallel illumination, an in-column energy filter, and a stable rotational goniometer stage. Rotational diffraction data were collected in an unsupervised manner from crystals of a heme-binding enzyme catalase and a representative organic semiconductor material Ph-BTBT-C10. The structures were determined by molecular replacement for catalase and by the direct method for Ph-BTBT-C10. The analyses demonstrate that the system works well for electron 3D crystallography of these molecules with less damaging, a smaller point spread, and less noise than using the conventional scintillator-coupled camera.

Keywords: CRYO ARM; DE64; eEFD; electron 3D crystallography (3D ED/MicroED); energy filter.