Surprises and pitfalls arising from (pseudo)symmetry.
It is not uncommon for protein crystals to crystallize with more than a single molecule per asymmetric unit. When more than a single molecule is present in the asymmetric unit, various pathological situations such as twinning, modulated crystals and pseudo translational or rotational symmetry can arise. The presence of pseudosymmetry can lead to uncertainties about the correct space group, especially in the presence of twinning. The background to certain common pathologies is presented and a new notation for space groups in unusual settings is introduced. The main concepts are illustrated with several examples from the literature and the Protein Data Bank.
Zwart
Peter H
PH
Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, One Cyclotron Road, Building 6R2100, Berkeley, CA 94720, USA. phzwart@lbl.gov
Grosse-Kunstleve
Ralf W
RW
Lebedev
Andrey A
AA
Murshudov
Garib N
GN
Adams
Paul D
PD
D000465:Algorithms; D018360:Crystallography, X-Ray / Q000379:methods*; D030562:Databases, Protein; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*
D011506:Proteins