title: Structural biology of the lanthanides-mining rare earths in the Protein Data Bank.
abstract: With its about 100,000 three-dimensional structures, the Protein Data Bank is a copious source of information: it contains also some hundreds of structures of macromolecules complexed with lanthanide cations, which are examined here. These cations, which are found in a wide variety of protein types, were introduced to determine the structures, by exploiting their anomalous dispersion (in crystallographic studies, where they are also used as crystallization additives) or the paramagnetic pseudocontact shifts (in NMR analyses). The coordination numbers in the first coordination sphere are very variable, though they tend to be close to those that are observed in small molecules or in water solution. The coordination polyhedra are also quite variable as it can be expected for large cations. Interestingly, lanthanide cations are frequently observed in packing bridges between symmetry equivalent molecules in crystals, where they tend to form polynuclear complexes, with up to seven cations bridged by water/hydroxide ligands.
authors.affiliation: Max F. Perutz Laboratories, University of Vienna, 5 Campus Vienna Biocenter, A-1030, Austria; Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Askerceva 5, SI-1000 Ljubljana, Slovenia.
authors.forename: Kristina
authors.initials: K
authors.lastname: Djinovic-Carugo
authors.affiliation: Department of Chemistry, University of Pavia, Viale Taramelli 12, I-27100 Pavia, Italy. Electronic address: olicar04@unipv.it.
authors.forename: Oliviero
authors.initials: O
authors.lastname: Carugo
mesh_terms: D018360:Crystallography, X-Ray; D030562:Databases, Protein; D028581:Lanthanoid Series Elements / Q000737:chemistry* / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D028581:Lanthanoid Series Elements; D011506:Proteins
keywords: Clusters; Coordination number; Coordination polyhedron; Lanthanides; Packing bridge; Protein Data Bank