title: Structure of oxalate-substituted diferric mare lactoferrin at 2.7 A resolution.
abstract: Lactoferrin binds two Fe(3+) and two CO(2-)(3) ions with high affinity. It can also bind other metal ions and anions. In order to determine the perturbations in the environments of the binding sites in the N and C lobes and elsewhere in the protein, the crystal structure of oxalate-substituted diferric mare lactoferrin has been determined at 2.7 A resolution. The final model has a crystallographic R factor of 21.3% for all data in the resolution range 17.0-2.7 A. The substitution of an oxalate anion does not perturb the overall structure of the protein, but produces several significant changes at the metal-binding and anion-binding sites. The binding of the oxalate anion is symmetrical in both the N and C lobes, unlike in diferric dioxalate human lactoferrin, where the oxalate anion binds the metal ion symmetrically in the C lobe and asymmetrically in the N lobe.
authors.affiliation: Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India.
authors.forename: A K
authors.initials: AK
authors.lastname: Sharma
authors.forename: T P
authors.initials: TP
authors.lastname: Singh
mesh_terms: D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D005260:Female; D006736:Horses; D006860:Hydrogen Bonding; D007501:Iron / Q000737:chemistry; D007781:Lactoferrin / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019159:Nonheme Iron Proteins / Q000737:chemistry; D010070:Oxalates / Q000737:chemistry; D017510:Protein Folding
chemical_list: D019159:Nonheme Iron Proteins; D010070:Oxalates; D007501:Iron; D007781:Lactoferrin