Multivariate estimation of substructure amplitudes for a single-wavelength anomalous diffraction experiment.
Acta Crystallogr D Struct Biol
; 79(Pt 4): 339-344, 2023 Apr 01.
Article
em En
| MEDLINE
| ID: mdl-36974967
ABSTRACT
To determine a substructure from single-wavelength anomalous diffraction (SAD) data using Patterson or direct methods, the substructure-factor amplitude (|Fa|) is first estimated. Currently, the absolute value of the Bijvoet difference is widely used as an estimate of |Fa| values for SAD data. Here, an equation is derived from multivariate statistics and tested that takes into account the correlation between the observed positive (F+) and negative (F-) Friedel pairs and Fa along with measurement errors in the observed data. The multivariate estimation of |Fa| has been implemented in a new program, Afro. Results on over 180 test cases show that Afro provides a higher correlation to the final substructure-factor amplitudes (calculated from the refined, final substructures) than the Bijvoet differences and improves the robustness of direct-methods substructure detection.
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MEDLINE
Assunto principal:
Cristalografia por Raios X
Idioma:
En
Ano de publicação:
2023
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Article