title: Molecular replacement--historical background.
abstract: A review is given of the mathematical procedures required for a molecular-replacement structure determination. These apply equally to the more frequently encountered situations where a known homologous structure can be used as a search model and to phase determination in the presence of non-crystallographic symmetry (NCS). In general, the former represents improper NCS between two different unit cells, whereas the latter occurs when there is proper NCS within one unit cell.
authors.affiliation: Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392, USA. mgr@indiana.bio.purdue.edu
authors.forename: M G
authors.initials: MG
authors.lastname: Rossmann
mesh_terms: D003461:Crystallography; D006454:Hemoglobins / Q000737:chemistry; D007328:Insulin / Q000737:chemistry; D008433:Mathematics; D008956:Models, Chemical; D008958:Models, Molecular
chemical_list: D006454:Hemoglobins; D007328:Insulin