|Entry||Database: EMDB / ID: EMD-4698|
|Title||Mouse apoferritin from data collected at liquid helium temperatureFerritin|
|Biological species||Mus musculus (house mouse)|
|Method||single particle reconstruction / cryo EM / Resolution: 2.8 Å|
|Authors||Pfeil-Gardiner O / Mills DJ / Vonck J / Kuehlbrandt W|
|Citation||Journal: IUCrJ / Year: 2019|
Title: A comparative study of single-particle cryo-EM with liquid-nitrogen and liquid-helium cooling.
Authors: Olivia Pfeil-Gardiner / Deryck J Mills / Janet Vonck / Werner Kuehlbrandt /
Abstract: Radiation damage is the most fundamental limitation for achieving high resolution in electron cryo-microscopy (cryo-EM) of biological samples. The effects of radiation damage are reduced by liquid- ...Radiation damage is the most fundamental limitation for achieving high resolution in electron cryo-microscopy (cryo-EM) of biological samples. The effects of radiation damage are reduced by liquid-helium cooling, although the use of liquid helium is more challenging than that of liquid nitrogen. To date, the benefits of liquid-nitrogen and liquid-helium cooling for single-particle cryo-EM have not been compared quantitatively. With recent technical and computational advances in cryo-EM image recording and processing, such a comparison now seems timely. This study aims to evaluate the relative merits of liquid-helium cooling in present-day single-particle analysis, taking advantage of direct electron detectors. Two data sets for recombinant mouse heavy-chain apoferritin cooled with liquid-nitrogen or liquid-helium to 85 or 17 K were collected, processed and compared. No improvement in terms of resolution or Coulomb potential map quality was found for liquid-helium cooling. Interestingly, beam-induced motion was found to be significantly higher with liquid-helium cooling, especially within the most valuable first few frames of an exposure, thus counteracting any potential benefit of better cryoprotection that liquid-helium cooling may offer for single-particle cryo-EM.
|Structure viewer||EM map: |
Downloads & links
|File||Download / File: emd_4698.map.gz / Format: CCP4 / Size: 20.8 MB / Type: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES)|
|Projections & slices|
Images are generated by Spider.
|Voxel size||X=Y=Z: 1.12 Å|
|Symmetry||Space group: 1|
CCP4 map header:
|Entire||Name: apoferritinFerritin / Number of components: 1|
-Component #1: protein, apoferritin
|Protein||Name: apoferritinFerritin / Recombinant expression: No|
|Mass||Theoretical: 500 kDa|
|Source||Species: Mus musculus (house mouse)|
|Source (engineered)||Expression System: Escherichia coli (E. coli)|
|Specimen||Specimen state: Particle / Method: cryo EM|
|Sample solution||Specimen conc.: 1.5 mg/mL / pH: 7.5|
|Vitrification||Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Temperature: 283 K / Humidity: 100 %|
-Electron microscopy imaging
|Imaging||Microscope: JEOL 3200FSC|
|Electron gun||Electron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Electron dose: 72 e/Å2 / Illumination mode: FLOOD BEAM|
|Lens||Magnification: 30000.0 X (nominal), 44642.0 X (calibrated) / Cs: 4.2 mm / Imaging mode: BRIGHT FIELD / Energy filter: In-column Omega Filter|
|Specimen Holder||Model: JEOL / Temperature: (17.0 - 17.0 K)|
|Camera||Detector: GATAN K2 SUMMIT (4k x 4k)|
|Image acquisition||Number of digital images: 233|
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