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Maximum-likelihood density modification

A likelihood-based approach to density modification is developed that can be applied to a wide variety of cases where some information about the electron density at various points in the unit cell is available. The key to the approach consists of developing likelihood functions that represent the pr...

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Detalles Bibliográficos
Autor principal: Terwilliger, Thomas C.
Formato: Texto
Lenguaje:English
Publicado: International Union of Crystallography 2000
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2792768/
https://www.ncbi.nlm.nih.gov/pubmed/10944333
http://dx.doi.org/10.1107/S0907444900005072
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author Terwilliger, Thomas C.
author_facet Terwilliger, Thomas C.
author_sort Terwilliger, Thomas C.
collection PubMed
description A likelihood-based approach to density modification is developed that can be applied to a wide variety of cases where some information about the electron density at various points in the unit cell is available. The key to the approach consists of developing likelihood functions that represent the probability that a particular value of electron density is consistent with prior expectations for the electron density at that point in the unit cell. These likelihood functions are then combined with likelihood functions based on experimental observations and with others containing any prior knowledge about structure factors to form a combined likelihood function for each structure factor. A simple and general approach to maximizing the combined likelihood function is developed. It is found that this likelihood-based approach yields greater phase improvement in model and real test cases than either conventional solvent flattening and histogram matching or a recent reciprocal-space solvent-flattening procedure [Terwilliger (1999 ▶), Acta Cryst. D55, 1863–1871].
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spelling pubmed-27927682009-12-14 Maximum-likelihood density modification Terwilliger, Thomas C. Acta Crystallogr D Biol Crystallogr Research Papers A likelihood-based approach to density modification is developed that can be applied to a wide variety of cases where some information about the electron density at various points in the unit cell is available. The key to the approach consists of developing likelihood functions that represent the probability that a particular value of electron density is consistent with prior expectations for the electron density at that point in the unit cell. These likelihood functions are then combined with likelihood functions based on experimental observations and with others containing any prior knowledge about structure factors to form a combined likelihood function for each structure factor. A simple and general approach to maximizing the combined likelihood function is developed. It is found that this likelihood-based approach yields greater phase improvement in model and real test cases than either conventional solvent flattening and histogram matching or a recent reciprocal-space solvent-flattening procedure [Terwilliger (1999 ▶), Acta Cryst. D55, 1863–1871]. International Union of Crystallography 2000-08-01 /pmc/articles/PMC2792768/ /pubmed/10944333 http://dx.doi.org/10.1107/S0907444900005072 Text en © International Union of Crystallography 2000 http://journals.iucr.org/services/termsofuse.html This is an open-access article distributed under the terms described at http://journals.iucr.org/services/termsofuse.html.
spellingShingle Research Papers
Terwilliger, Thomas C.
Maximum-likelihood density modification
title Maximum-likelihood density modification
title_full Maximum-likelihood density modification
title_fullStr Maximum-likelihood density modification
title_full_unstemmed Maximum-likelihood density modification
title_short Maximum-likelihood density modification
title_sort maximum-likelihood density modification
topic Research Papers
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2792768/
https://www.ncbi.nlm.nih.gov/pubmed/10944333
http://dx.doi.org/10.1107/S0907444900005072
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