WikiSysop at 07:35, 29 April 2009

2009-04-29T07:35:47Z

New page

== Citation ==

Saad A, Ludtke SJ, Jakana J, Rixon FJ, Tsuruta H, Chiu W (2001) Fourier
amplitude decay of electron cryomicroscopic images of single
particles and eVects on structure determination. J Struct Biol
133:32–42

[http://scholar.google.com/scholar?hl=en&lr=&newwindow=1&cites=16537780180480634810 Cited by]

== Abstract ==

Several factors, including spatial and temporal coherence of the electron microscope, specimen movement, recording medium, and scanner optics, contribute to the decay of the measured Fourier amplitude in electron image intensities. We approximate the combination of these factors as a single Gaussian envelope function, the width of which is described by a single experimental B-factor. We present an improved method for estimating this B-factor from individual micrographs by combining the use of X-ray solution scattering and numerical fitting to the average power spectrum of particle images. A statistical estimation from over 200 micrographs of herpes simplex virus type-1 capsids was used to estimate the spread in the experimental B-factor of the data set. The B-factor is experimentally shown to be dependent on the objective lens defocus setting of the microscope. The average B-factor, the X-ray scattering intensity of the specimen, and the number of particles required to determine the structure at a lower resolution can be used to estimate the minimum fold increase in the number of particles that would be required to extend a single particle reconstruction to a specified higher resolution. We conclude that microscope and imaging improvements to reduce the experimental B-factor will be critical for obtaining an atomic resolution structure.

== Keywords ==

== Links ==

Article http://www.ncbi.nlm.nih.gov/pubmed/11356062

== Related software ==

== Related methods ==

== Comments ==

2001Saad CTFEstimate - Revision history

WikiSysop at 07:35, 29 April 2009