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Induction of a spectroscopically defined transition by guanidinium hydrochloride on a recombinant calcium binding protein from Entamoeba histolytica

Gopal, B and Krishna Rao, JV and Thomas, CJ and Bhattacharya, A and Bhattacharya, S and Murthy, MRN and Surolia, A (1998) Induction of a spectroscopically defined transition by guanidinium hydrochloride on a recombinant calcium binding protein from Entamoeba histolytica. In: FEBS Letters, 441 (01). pp. 71-76.

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Abstract

Sequence analysis and metal ion binding studies reported earlier have established that the calcium binding protein (CaBP) from the parasitic ameboid Entamoeba histolytica protein has four canonical EF hand motifs which bind calcium. Equilibrium denaturation studies on both the apo and the hole forms of this protein indicate the presence of stable transition intermediates at low denaturant concentrations as revealed by the binding of the non-specific hydrophobic dye ANS. Fast reaction kinetics shows that the binding of the Gdn(+) ions at or near the Ca2+ sites in the N-terminal domain influences metal ion binding to the sites in the C-terminal domain. Isothermal calorimetric titrations performed using low GdnHCl concentrations reveal the presence of two binding sites of low affinity, both being endothermic in nature. Thus the stabilization of CaBP observed at low GdnHCl concentration represents a native-like intermediate, with the Gdn(+) ions mimicking Ca2+ binding at the N-terminal domain of this protein.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Federation of European Biochemical Societies.
Keywords: Calcium binding protein;Unfolding,binding and stabilization by guanidinium ion.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 21 Aug 2009 10:15
Last Modified: 19 Sep 2010 05:25
URI: http://eprints.iisc.ernet.in/id/eprint/18724

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