Three-dimensional electron diffraction (3D ED) is a measurement and analysis technique in transmission electron microscopy that is used for determining atomic structures from small crystals. Diverse targets such as proteins, polypeptides, and organic compounds, whose crystals exist in aqueous solutions and organic solvents, or as dried powders, can be studied with 3D ED. We have been involved in the development of this technique, which can now rapidly process a large number of data collected through AI control, enabling efficient structure determination.
View Article and Find Full Text PDFEnantioselectivity of helical aggregation is conventionally directed either by its homochiral ingredients or by introduction of chiral catalysis. The fundamental question, then, is whether helical aggregation that consists only of achiral components can obtain enantioselectivity in the absence of chiral catalysis. Here, by exploiting enantiospecific interaction due to chiral-induced spin selectivity (CISS) that has been known to work to enantio-separate a racemic mixture of chiral molecules, we demonstrate the enantioselectivity in the assembly of mesoscale helical supramolecules consisting of achiral cobalt phthalocyanines.
View Article and Find Full Text PDFHydrogen bonding, bond polarity, and charges in protein molecules play critical roles in the stabilization of protein structures, as well as affecting their functions such as enzymatic catalysis, electron transfer, and ligand binding. These effects can potentially be measured in Coulomb potentials using cryogenic electron microscopy (cryo-EM). We here present charges and bond properties of hydrogen in a sub-1.
View Article and Find Full Text PDFStructure analysis of small crystals is important in areas ranging from synthetic organic chemistry to pharmaceutical and material sciences, as many compounds do not yield large crystals. Here we present the detailed characterization of the structure of an organic molecule, rhodamine-6G, determined at a resolution of 0.82 Å by an X-ray free-electron laser (XFEL).
View Article and Find Full Text PDFProc Natl Acad Sci U S A
September 2022
In cryo-electron microscopy (cryo-EM) data collection, locating a target object is error-prone. Here, we present a machine learning-based approach with a real-time object locator named yoneoLocr using YOLO, a well-known object detection system. Implementation shows its effectiveness in rapidly and precisely locating carbon holes in single particle cryo-EM and in locating crystals and evaluating electron diffraction (ED) patterns in automated cryo-electron crystallography (cryo-EX) data collection.
View Article and Find Full Text PDFThe layered structures of graphite and related nanographene molecules play key roles in their physical and electronic functions. However, the stacking modes of negatively curved nanographenes remain unclear, owing to the lack of suitable nanographene molecules. Herein, we report the synthesis and one-dimensional supramolecular self-assembly of negatively curved nanographenes without any assembly-assisting substituents.
View Article and Find Full Text PDFElectron 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.
View Article and Find Full Text PDFA semi-automated protocol has been developed for rotational data collection of electron diffraction patterns by combined use of SerialEM and ParallEM, where SerialEM is used for positioning of sample crystals and ParallEM for rotational data collection. ParallEM calls standard camera control software through an AutoIt script, which adapts to software operational changes and to new GUI programs guiding other cameras. Development included periodic flashing and pausing of data collection during overnight or day-long recording with a cold field-emission beam.
View Article and Find Full Text PDFActa Crystallogr D Struct Biol
December 2019
Hydrogen atoms are critical to the nature and properties of proteins, and thus deuteration has the potential to influence protein function. In fact, it has been reported that some deuterated proteins show different physical and chemical properties to their protiated counterparts. Consequently, it is important to investigate protonation states around the active site when using deuterated proteins.
View Article and Find Full Text PDFGreen fluorescent protein (GFP) is a light-emitting protein that does not require a prosthetic group for its fluorescent activity. As such, GFP has become indispensable as a molecular tool in molecular biology. Nonetheless, there has been no subatomic elucidation of the GFP structure owing to the structural polymorphism around the chromophore.
View Article and Find Full Text PDFFlavin compounds such as flavin adenine dinucleotide (FAD), flavin mononucleotide and riboflavin make up the active centers in flavoproteins that facilitate various oxidoreductive processes. The fine structural features of the hydrogens and valence electrons of the flavin molecules in the protein environment are critical to the functions of the flavoproteins. However, information on these features cannot be obtained from conventional protein X-ray analyses at ordinary resolution.
View Article and Find Full Text PDFNADH-Cytochrome b5 reductase (b5R), a flavoprotein consisting of NADH and flavin adenine dinucleotide (FAD) binding domains, catalyzes electron transfer from the two-electron carrier NADH to the one-electron carrier cytochrome b5 (Cb5). The crystal structures of both the fully reduced form and the oxidized form of porcine liver b5R were determined. In the reduced b5R structure determined at 1.
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