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Title: Dose, exposure time, and resolution in Serial X-ray Crystallography

Abstract

Using detailed simulation and analytical models, the exposure time is estimated for serial crystallography, where hydrated laser-aligned proteins are sprayed across a continuous synchrotron beam. The resolution of X-ray diffraction microscopy is limited by the maximum dose that can be delivered prior to sample damage. In the proposed Serial Crystallography method, the damage problem is addressed by distributing the total dose over many identical hydrated macromolecules running continuously in a single-file train across a continuous X-ray beam, and resolution is then limited only by the available fluxes of molecules and X-rays. Orientation of the diffracting molecules is achieved by laser alignment. We evaluate the incident X-ray fluence (energy/area) required to obtain a given resolution from (1) an analytical model, giving the count rate at the maximum scattering angle for a model protein, (2) explicit simulation of diffraction patterns for a GroEL-GroES protein complex, and (3) the frequency cut off of the transfer function following iterative solution of the phase problem, and reconstruction of a density map in the projection approximation. These calculations include counting shot noise and multiple starts of the phasing algorithm. The results indicate the number of proteins needed within the beam at any instant for a givenmore » resolution and X-ray flux. We confirm an inverse fourth power dependence of exposure time on resolution, with important implications for all coherent X-ray imaging. We find that multiple single-file protein beams will be needed for sub-nanometer resolution on current third generation synchrotrons, but not on fourth generation designs, where reconstruction of secondary protein structure at a resolution of 7 {angstrom} should be possible with short (below 100 s) exposures.« less

Authors:
; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
991522
Report Number(s):
UCRL-JRNL-229466
TRN: US1007501
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: Jounal of Synchrotron Research, vol. 15, no. 1, January 1, 2008, pp. 62-73; Journal Volume: 15; Journal Issue: 1
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUMM MECHANICS, GENERAL PHYSICS; 59 BASIC BIOLOGICAL SCIENCES; ALIGNMENT; COHERENT SCATTERING; CRYSTALLOGRAPHY; DIFFRACTION; LASERS; MICROSCOPY; ORIENTATION; PROTEIN STRUCTURE; PROTEINS; RESOLUTION; SCATTERING; SIMULATION; SYNCHROTRONS; TRANSFER FUNCTIONS; X-RAY DIFFRACTION

Citation Formats

Starodub, D, Rez, P, Hembree, G, Howells, M, Shapiro, D, Chapman, H N, Fromme, P, Schmidt, K, Weierstall, U, Doak, R B, and Spence, J C. Dose, exposure time, and resolution in Serial X-ray Crystallography. United States: N. p., 2007. Web.
Starodub, D, Rez, P, Hembree, G, Howells, M, Shapiro, D, Chapman, H N, Fromme, P, Schmidt, K, Weierstall, U, Doak, R B, & Spence, J C. Dose, exposure time, and resolution in Serial X-ray Crystallography. United States.
Starodub, D, Rez, P, Hembree, G, Howells, M, Shapiro, D, Chapman, H N, Fromme, P, Schmidt, K, Weierstall, U, Doak, R B, and Spence, J C. Thu . "Dose, exposure time, and resolution in Serial X-ray Crystallography". United States. doi:. https://www.osti.gov/servlets/purl/991522.
@article{osti_991522,
title = {Dose, exposure time, and resolution in Serial X-ray Crystallography},
author = {Starodub, D and Rez, P and Hembree, G and Howells, M and Shapiro, D and Chapman, H N and Fromme, P and Schmidt, K and Weierstall, U and Doak, R B and Spence, J C},
abstractNote = {Using detailed simulation and analytical models, the exposure time is estimated for serial crystallography, where hydrated laser-aligned proteins are sprayed across a continuous synchrotron beam. The resolution of X-ray diffraction microscopy is limited by the maximum dose that can be delivered prior to sample damage. In the proposed Serial Crystallography method, the damage problem is addressed by distributing the total dose over many identical hydrated macromolecules running continuously in a single-file train across a continuous X-ray beam, and resolution is then limited only by the available fluxes of molecules and X-rays. Orientation of the diffracting molecules is achieved by laser alignment. We evaluate the incident X-ray fluence (energy/area) required to obtain a given resolution from (1) an analytical model, giving the count rate at the maximum scattering angle for a model protein, (2) explicit simulation of diffraction patterns for a GroEL-GroES protein complex, and (3) the frequency cut off of the transfer function following iterative solution of the phase problem, and reconstruction of a density map in the projection approximation. These calculations include counting shot noise and multiple starts of the phasing algorithm. The results indicate the number of proteins needed within the beam at any instant for a given resolution and X-ray flux. We confirm an inverse fourth power dependence of exposure time on resolution, with important implications for all coherent X-ray imaging. We find that multiple single-file protein beams will be needed for sub-nanometer resolution on current third generation synchrotrons, but not on fourth generation designs, where reconstruction of secondary protein structure at a resolution of 7 {angstrom} should be possible with short (below 100 s) exposures.},
doi = {},
journal = {Jounal of Synchrotron Research, vol. 15, no. 1, January 1, 2008, pp. 62-73},
number = 1,
volume = 15,
place = {United States},
year = {Thu Mar 22 00:00:00 EDT 2007},
month = {Thu Mar 22 00:00:00 EDT 2007}
}