title: Structure of buffalo lactoferrin at 2.5 A resolution using crystals grown at 303 K shows different orientations of the N and C lobes.
abstract: The structure of buffalo lactoferrin has been determined at 303 K. The crystals belong to orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 77.5, b = 91.0, c = 131.5 A and Z = 4. The structure has been refined to an R factor of 0.187. The overall structure of the protein is similar to its structure determined at 277 K in a different crystal form. However, the lobe orientations in the two structures differ by 9.0 degrees, suggesting significant inter-lobe flexibility in this family of proteins. The inter-lobe interactions are predominantly hydrophobic and could act as a cushion for a change in orientation under the influence of external conditions. On the other hand, the domain arrangements are found to be similar in 277 and 303 K crystal structures, with orientations differing by 1.5 and 1.0 degrees in the N and C lobes, respectively. The results of these investigations suggest that the increase in temperature helps in the production of better quality crystals.
authors.affiliation: Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India.
authors.forename: S
authors.initials: S
authors.lastname: Karthikeyan
authors.forename: M
authors.initials: M
authors.lastname: Paramasivam
authors.forename: S
authors.initials: S
authors.lastname: Yadav
authors.forename: A
authors.initials: A
authors.lastname: Srinivasan
authors.forename: T P
authors.initials: TP
authors.lastname: Singh
mesh_terms: D000818:Animals; D001665:Binding Sites; D002020:Buffaloes; D003460:Crystallization; D018360:Crystallography, X-Ray; D005260:Female; D006031:Glycosylation; D006860:Hydrogen Bonding; D007501:Iron / Q000737:chemistry; D007781:Lactoferrin / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017510:Protein Folding; D013696:Temperature
chemical_list: D007501:Iron; D007781:Lactoferrin