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The Pseudo-Atom Approximation in Direct Phase Determination of Protein Structures.

Published online by Cambridge University Press:  02 July 2020

Douglas L. Dorset
Douglas L. Dorset*
Affiliation:
Electron Diffraction Department, Hauptman-Woodward Medical Research Institute, 73 High Street, Buffalo, New York14203-1196
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Extract

In principle, the availability of high-resolution micrographs in electron crystallography is a direct solution of the phase problem that has been used to great advantage for the study of proteins. However, as the resolution of the determination increases, the Fourier transform of the micrograph becomes a less accurate phase source. Hence, alternative direct methods for phase determination have been evaluated, if only to extend the resolution of most reliable lower resolution phases to the limit of the electron diffraction pattern. The first demonstration of its feasibility was published in a study of bacteriorhodopsin extending 15 Å image phases to beyond 3 Å by maximum entropy and likelihood procedures i. Later studies demonstrated that convolutional methods also can be effective.

In protein crystallography, there is always an interest in carrying out a true ab initio determinations, if only because of the challenge to traditional direct methods that become statistically less reliable as the number of atoms in the unit cell increases.

Type
Electron Crystallography; The Electron Phase Problem
Information
Microscopy and Microanalysis , Volume 3 , Issue S2: Proceedings: Microscopy & Microanalysis '97, Microscopy Society of America 55th Annual Meeting, Microbeam Analysis Society 31st Annual Meeting, Histochemical Society 48th Annual Meeting, Cleveland, Ohio, August 10-14, 1997 , August 1997 , pp. 1025 - 1026
Copyright
Copyright © Microscopy Society of America 1997

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References

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