Application of a real-space three-dimensional image reconstruction method in the structural analysis of noncrystalline biological macromolecules enveloped by water in coherent x-ray diffraction microscopy

Wataru Kodama, Masayoshi Nakasako

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Coherent x-ray diffraction microscopy is a novel technique in the structural analyses of particles that are difficult to crystallize, such as the biological particles composing living cells. As water is indispensable for maintaining particles in functional structures, sufficient hydration of targeted particles is required during sample preparation for diffraction microscopy experiments. However, the water enveloping particles also contributes significantly to the diffraction patterns and reduces the electron-density contrast of the sample particles. In this study, we propose a protocol for the structural analyses of particles in water by applying a three-dimensional reconstruction method in real space for the projection images phase-retrieved from diffraction patterns, together with a developed density modification technique. We examined the feasibility of the protocol through three simulations involving a protein molecule in a vacuum, and enveloped in either a droplet or a cube-shaped water. The simulations were carried out for the diffraction patterns in the reciprocal planes normal to the incident x-ray beam. This assumption and the simulation conditions corresponded to experiments using x-ray wavelengths of shorter than 0.03 Å The analyses demonstrated that our protocol provided an interpretable electron-density map. Based on the results, we discuss the advantages and limitations of the proposed protocol and its practical application for experimental data. In particular, we examined the influence of Poisson noise in diffraction patterns on the reconstructed three-dimensional electron density in the proposed protocol.

Original languageEnglish
Article number021902
JournalPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
Volume84
Issue number2
DOIs
Publication statusPublished - 2011 Aug 3

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Statistics and Probability
  • Condensed Matter Physics

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