Pair Distribution Function from Electron Diffraction in Cryogenic Electron Microscopy: Revealing Glassy Water Structure
Abstract: In recent years, cryogenic electron microscopy (Cryo-EM) has revolutionized the structure determination of wet samples and especially that of biological macromolecules. The glassy-water medium in which the molecules are embedded is considered an almost in vivo environment for biological samples. The local structure of amorphous ice is known from neutron- and X-ray-diffraction studies, techniques appropriate for much larger volumes than those used in cryo-EM. We here present a first study of the pair-distribution function g(r) of glassy water under cryo-EM conditions using electron diffraction data. We found g(r) to be between that of low-density amorphous ice and that of supercooled water. Under electron exposure, cubic-ice regions were found to nucleate in thicker glassy-water samples. Our work enables to obtain quantitative structural information using g(r) from cryo-EM.
Author(s): Souza, JB Schleder, GR; Colombari, FM ; de Farias, MA ; Bettini, J ; van Heel, M ; Portugal, RV; Fazzio, A ; Leite, ER
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
Published: FEB 20 2020 Volume: 11 Pages: 1564-1569
DOI: 10.1021/acs.jpclett.0c00171
