title: Structural basis for sequential displacement of Ca(2+) by Yb(3+) in a protozoan EF-hand calcium binding protein.
abstract: We have studied the displacement of Ca(2+)by the trivalent lanthanide ions (Yb(3+)) in a protozoan (Entamoeba histolytica) Ca(2+)-binding protein (EhCaBP), by NMR and thermodynamics. We have demonstrated, for the first time, how one can use in a combined fashion the utility of NMR and thermodynamics to have an insight to the relative binding specificities/affinity between Ca(2+) and Yb(3+). As revealed by the titration experiments, Yb(3+) displaces Ca(2+) from the four metal binding sites present in EhCaBP in a sequential manner. The study provides a structural origin for such a sequential Ca(2+) displacement by Yb(3+) in EhCaBP.
authors.affiliation: Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai-400005 India.
authors.forename: Hanudatta S
authors.initials: HS
authors.lastname: Atreya
authors.forename: Sulakshana
authors.initials: S
authors.lastname: Mukherjee
authors.forename: Kandala V R
authors.initials: KV
authors.lastname: Chary
authors.forename: Yong-Min
authors.initials: YM
authors.lastname: Lee
authors.forename: Claudio
authors.initials: C
authors.lastname: Luchinat
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000737:chemistry*; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D004748:Entamoeba histolytica / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D015800:Protozoan Proteins / Q000737:chemistry* / Q000378:metabolism; D013816:Thermodynamics; D015018:Ytterbium / Q000737:chemistry*
chemical_list: D002135:Calcium-Binding Proteins; D015800:Protozoan Proteins; C075554:calcium-binding protein, Entamoeba histolytica; D015018:Ytterbium; D002118:Calcium