2i18
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(New page: 200px<br /><applet load="2i18" size="450" color="white" frame="true" align="right" spinBox="true" caption="2i18" /> '''The refined structure of C-terminal domain o...)
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Revision as of 09:58, 21 November 2007
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The refined structure of C-terminal domain of an EF-hand Calcium binding Protein from Entamoeba Histolytica
Overview
Lanthanide ions (Ln(3+)), which have ionic radii similar to those of, Ca(2+), can displace the latter in a calcium binding protein, without, affecting its tertiary structure. The paramagnetic Ln(3+) possesses large, anisotropic magnetic susceptibilities and produce pseudocontact shifts, (PCSs), which have r(-3) dependence. The PCS can be seen for spins as far, as 45 A from the paramagnetic ion. They aid in structure refinement of, proteins by providing long-range distance constraints. Besides, they can, be used to determine the interdomain orientation in multidomain proteins., This is particularly important in the context of a calcium binding protein, from Entamoeba histolytica (EhCaBP), which consists of two globular, domains connected by a flexible linker region containing 8 residues. As a, first step to obtain the interdomain orientation in EhCaBP, a suite of 2D, and 3D heteronuclear experiments were recorded on EhCaBP by displacing, calcium with Ce(3+), Ho(3+), Er(3+), Tm(3+), Dy(3+), and Yb(3+) ions in, separate experiments, and the PCS of (1)H(N) and (15)N spins were, measured. Such data have been used in the refinement of the individual, domain structures of the protein in parallel with the calculation of the, respective magnetic anisotropy tensorial values, which differ, substantially (2.1-2.8 times) from what is found in other Ca(2+) binding, loops. This study provides a structural basis for such variations in the, magnetic anisotropy tensorial values.
About this Structure
2I18 is a Single protein structure of sequence from Entamoeba histolytica with LA as ligand. This structure superseeds the now removed PDB entry 2EV7. Full crystallographic information is available from OCA.
Reference
Structural basis for the observed differential magnetic anisotropic tensorial values in calcium binding proteins., Mustafi SM, Mukherjee S, Chary KV, Cavallaro G, Proteins. 2006 Nov 15;65(3):656-69. PMID:16981203
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