Symmetry and space groups

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

The crystallographic toolbox is at [1]. Its predecessor, SgInfo, is here.

Facts about space groups

There are 230 space groups, 65 of which accessible to proteins.

Empirically, P2₁2₁2₁ is the space group which occurs most often (23%) in the PDB; second place is P₁ with 14.4% ( [2]).