Symmetry and space groups

Space group operators can be found here: http://www.embl-hamburg.de/~pinotsis/spacegroup.html

Empirically, P2_{1}2_{1}2_{1} is the space group which occurs most often in the PDB (23%); second place is P2_{1} with 14.4% ( http://www.rcsb.org/pdb/statistics/histogram.do?mdcat=symmetry&mditem=space_group_name_H-M&numOfbars=200).