Open AccessOn optimal placement of molecules in the unit cell
Author(s) -
Dauter Zbigniew
Publication year - 2013
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
ISSN - 1399-0047
DOI - 10.1107/s0907444913002722
Subject(s) - symmetry (geometry) , macromolecule , symmetry operation , lattice (music) , protein data bank (rcsb pdb) , crystallography , unit (ring theory) , computer science , crystal structure , space (punctuation) , protein data bank , space group , rotational symmetry , theoretical physics , physics , chemistry , mathematics , stereochemistry , protein structure , geometry , quantum mechanics , x ray crystallography , nuclear magnetic resonance , diffraction , biochemistry , mathematics education , acoustics , operating system
There are currently no rules for a unified, standard way of placing macromolecular structures in the crystal lattice. An analysis of all possible symmetry‐equivalent representations of molecular structures in various space groups leads to the concept of the anti‐Cheshire symmetry and suggests that the center of a unique structural motif can always be placed within the selected asymmetric unit of the anti‐Cheshire cell. The placement of structures according to this suggestion will ensure uniformity of presentation of all structurally equivalent Protein Data Bank models and will therefore diminish the possibility of confusing less crystallographically knowledgeable users of the PDB. The anti‐Cheshire cells and their asymmetric units are defined and tabulated for all 65 space groups relevant to macromolecular crystallography that exhibit only rotational symmetry operations.