Structural basis for sequential displacement of Ca(2+) by Yb(3+) in a protozoan EF-hand calcium binding protein |
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Authors: | Atreya Hanudatta S Mukherjee Sulakshana Chary Kandala V R Lee Yong-Min Luchinat Claudio |
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Affiliation: | Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai-400005 India. |
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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. |
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Keywords: | EF-hand protein calmodulin EhCaBP pseudocontact shifts chemical shifts ytterbium |
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