Content deleted Content added
ce |
No edit summary |
||
| (9 intermediate revisions by 5 users not shown) | |||
Line 1:
{{Short description|Method of analyzing transmission electron microscopy imagery}}
[[File:SingleParticleAnalysis.png|thumb|right|Single particle analysis segments and averages many particles from a sample, allowing for computer algorithms to process the individual images into a combined "representative" image. This allows for improvements in signal to noise, and can be combined with [[deconvolution]] to provide limited improvements to spatial resolution in the image.]]
'''Single particle analysis''' is a group of related computerized image processing techniques used to analyze images from [[Transmission electron microscope|transmission electron microscopy]] (TEM).<ref name="Frank">{{Cite book|first=Joachim |last=Frank |title=Three-dimensional electron microscopy of macromolecular assemblies: visualization of biological molecules in their native state |publisher=Oxford University Press |___location=Oxford |year=2006 |isbn=978-0-19-518218-7 |url=https://books.google.com/books?id=vWaSRUjicbgC}}{{Page needed|date=August 2010}}</ref> These methods were developed to improve and extend the information obtainable from TEM images of particulate samples, typically [[proteins]] or other large biological entities such as [[virus]]es. Individual images of stained or unstained particles are very [[Signal noise|noisy]],
==Techniques==
Line 44:
Various software [[Software tools for molecular microscopy|programs]] are available that allow viewing the 3D maps. These often enable the user to manually dock in protein coordinates (structures from [[X-ray crystallography]] or NMR) of subunits into the electron density. Several programs can also fit subunits computationally.<ref>{{cite web |title=Cryo-EM structure solution with Phenix |url=https://phenix-online.org/documentation/overviews/cryo-em_index.html |website=phenix-online.org}}</ref><ref>{{cite journal |last1=Nicholls |first1=RA |last2=Tykac |first2=M |last3=Kovalevskiy |first3=O |last4=Murshudov |first4=GN |title=Current approaches for the fitting and refinement of atomic models into cryo-EM maps using CCP-EM. |journal=Acta Crystallographica Section D |date=1 June 2018 |volume=74 |issue=Pt 6 |pages=492–505 |doi=10.1107/S2059798318007313 |pmid=29872001|pmc=6096485 |bibcode=2018AcCrD..74..492N |doi-access=free }}</ref>
For higher-resolution structures, it is possible to build the macromolecule directly, without prior structural knowledge from other methods. Computer algorithms have also been developed for this task.<ref>{{
As high-resolution cryo-EM models are relative new, quality control tools are not as plentiful as it is for X-ray models. Nevertheless, cryo-EM ("real space") versions of the [[difference density map]],<ref>{{cite journal |last1=Yamashita |first1=Keitaro |last2=Palmer |first2=Colin M. |last3=Burnley |first3=Tom |last4=Murshudov |first4=Garib N. |title=Cryo-EM single-particle structure refinement and map calculation using Servalcat |journal=Acta Crystallographica Section D
===Single particle ICP-MS===
Single particle-induced coupled plasma-mass spectroscopy (SP-ICP-MS) is used in several areas where there is the possibility of detecting and quantifying suspended particles in samples of environmental fluids, assessing their migration, assessing the size of particles and their distribution, and also determining their stability in a given environment. SP-ICP-MS was designed for particle suspensions in 2000 by Claude Degueldre. He first tested this new methodology at the Forel Institute of the University of Geneva and presented this new analytical approach at the 'Colloid 2oo2' symposium during the spring 2002 meeting of the EMRS, and in the proceedings in 2003.<ref>
==Examples==
Line 59:
==Primary database==
* [http://www.emdatabank.org/index.html EM Data Bank] {{Webarchive|url=https://web.archive.org/web/20190205053534/http://www.emdatabank.org/index.html |date=2019-02-05 }} ([[EM Data Bank]])
==References==
| |||