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Noncrystallographic symmetry‐constrained map obtained by direct density optimization
Author(s) -
Yoshimura Masato,
Chen Nai-Chi,
Guan Hong-Hsiang,
Chuankhayan Phimonphan,
Lin Chien-Chih,
Nakagawa Atsushi,
Chen Chun-Jung
Publication year - 2020
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.374
H-Index - 138
ISSN - 2059-7983
DOI - 10.1107/s2059798319017297
Subject(s) - symmetry (geometry) , physics , mathematics , geometry
Noncrystallographic symmetry (NCS) averaging following molecular‐replacement phasing is generally the major technique used to solve a structure with several molecules in one asymmetric unit, such as a spherical icosahedral viral particle. As an alternative method to NCS averaging, a new approach to optimize or to refine the electron density directly under NCS constraints is proposed. This method has the same effect as the conventional NCS‐averaging method but does not include the process of Fourier synthesis to generate the electron density from amplitudes and the corresponding phases. It has great merit for the solution of structures with limited data that are either twinned or incomplete at low resolution. This method was applied to the case of the T = 1 shell‐domain subviral particle of Penaeus vannamei nodavirus with data affected by twinning using the REFMAC 5 refinement software.