Single particle analysis

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 microscopy (TEM).[1] 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 viruses. Individual images of stained or unstained particles are very noisy, and so hard to interpret. Combining several digitized images of similar particles together gives an image with stronger and more easily interpretable features. An extension of this technique uses single particle methods to build up a three-dimensional reconstruction of the particle. Using cryo-electron microscopy it has become possible to generate reconstructions with sub-nanometer resolution and near-atomic resolution[2][3] first in the case of highly symmetric viruses, and now in smaller, asymmetric proteins as well.[4] Single particle analysis can also be performed by inductively coupled plasma mass spectrometry (ICP-MS).

  1. ^ Frank, Joachim (2006). Three-dimensional electron microscopy of macromolecular assemblies: visualization of biological molecules in their native state. Oxford: Oxford University Press. ISBN 978-0-19-518218-7.[page needed]
  2. ^ Zhou ZH (April 2008). "Towards atomic resolution structural determination by single-particle cryo-electron microscopy". Current Opinion in Structural Biology. 18 (2): 218–28. doi:10.1016/j.sbi.2008.03.004. PMC 2714865. PMID 18403197.
  3. ^ Wang Q, Matsui T, Domitrovic T, Zheng Y, Doerschuk PC, Johnson JE (March 2013). "Dynamics in cryo EM reconstructions visualized with maximum-likelihood derived variance maps". Journal of Structural Biology. 181 (3): 195–206. doi:10.1016/j.jsb.2012.11.005. PMC 3870017. PMID 23246781.
  4. ^ Bartesaghi, Alberto; Merk, Alan; Banerjee, Soojay; Matthies, Doreen; Wu, Xiongwu; Milne, Jacqueline L. S.; Subramaniam, Sriram (2015-06-05). "2.2 Å resolution CryoTEM structure of β-galactosidase in complex with a cell-permeant inhibitor". Science. 348 (6239): 1147–1151. Bibcode:2015Sci...348.1147B. doi:10.1126/science.aab1576. ISSN 1095-9203. PMC 6512338. PMID 25953817.