1clb
From Proteopedia
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DETERMINATION OF THE SOLUTION STRUCTURE OF APO CALBINDIN D9K BY NMR SPECTROSCOPY
Overview
The three-dimensional structure of apo calbindin D9k has been determined, using constraints generated from nuclear magnetic resonance spectroscopy., The family of solution structures was calculated using a combination of, distance geometry, restrained molecular dynamics, and hybrid relaxation, matrix analysis of the nuclear Overhauser effect (NOE) cross-peak, intensities. Errors and inconsistencies in the input constraints were, identified using complete relaxation matrix analyses based on the results, of preliminary structure calculations. The final input data consisted of, 994 NOE distance constraints and 122 dihedral constraints, aided by the, stereospecific assignment of the resonances from 21 beta-methylene groups, and seven isopropyl groups of leucine and valine residues. The resulting, family of 33 structures contain no violation of the distance constraints, greater than 0.17 A or of the dihedral angle constraints greater than 10, degrees. The structures consist of a well-defined, antiparallel four-helix, bundle, with a short anti-parallel beta-interaction between the two, unoccupied calcium-binding loops. The root-mean-square deviation from the, mean structure of the backbone heavy-atoms for the well-defined helical, residues is 0.55 A. The remainder of the ion-binding loops, the linker, loop connecting the two sub-domains of the protein, and the N and C, termini exhibit considerable disorder between different structures in the, ensemble. A comparison with the structure of the (Ca2+)2 state indicates, that the largest changes associated with ion-binding occur in the middle, of helix IV and in the packing of helix III onto the remainder of the, protein. The change in conformation of these helices is associated with a, subtle reorganization of many residues in the hydrophobic core, including, some side-chains that are up to 15 A from the ion-binding site.
About this Structure
1CLB is a Single protein structure of sequence from Bos taurus. Full crystallographic information is available from OCA.
Reference
Determination of the solution structure of Apo calbindin D9k by NMR spectroscopy., Skelton NJ, Kordel J, Chazin WJ, J Mol Biol. 1995 Jun 2;249(2):441-62. PMID:7783203
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