Cargando…
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...
Autor principal: | |
---|---|
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 |
_version_ | 1782175272442789888 |
---|---|
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]. |
format | Text |
id | pubmed-2792768 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2000 |
publisher | International Union of Crystallography |
record_format | MEDLINE/PubMed |
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 |
work_keys_str_mv | AT terwilligerthomasc maximumlikelihooddensitymodification |