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1ad7
From Proteopedia
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NMR STRUCTURE OF METAL-FREE CONANTOKIN G, 1 STRUCTURE
Overview
Conantokin G is a gamma-carboxyglutamic acid-containing conotoxin from the, venom of the marine cone snail Conus geographus. The 17-residue peptide, which contains five gamma-carboxyglutamic acid (Gla) residues and an, amidated C-terminal asparagine amide, was synthesized chemically in a form, identical to the natural conantokin G. To gain insight into the role of, gamma-carboxyglutamic acid in the structure of this peptide, we determined, the three-dimensional structure of conantokin G by 1H NMR and compared its, structure to other conotoxins and to the gamma-carboxyglutamic, acid-containing regions of the vitamin K-dependent blood-clotting, proteins. Complete resonance assignments were made by two-dimensional 1H, NMR spectroscopy in the absence of metal ions. NOE cross-peaks d(alphaN), d(NN), and d(betaN) provided interproton distance information, and vicinal, spin-spin coupling constants 3J(HN alpha) were used to calculate phi, torsion angles. Distance geometry and simulated annealing methods were, used to derive 20 convergent structures from a set of 227 interproton, distance restraints and 13 torsion angle measurements. The backbone rmsd, to the geometric average for 20 final structures is 0.8 +/- 0.1 A., Conantokin G consists of a structured region commencing at Gla 3 and, extending through arginine 13. This structure includes a partial loop, centered around Gla 3 and Gla 4, a distorted type I turn between glutamine, 6 and glutamine 9, and two type I turns involving Gla 10, leucine 11, and, isoleucine 12 and arginine 13. Together, these two turns define, approximately 1.6 turns of a distorted 3(10) helix. The observed structure, possesses structural elements similar to those seen in the, disulfide-linked conotoxins.
About this Structure
1AD7 is a Single protein structure of sequence from Conus geographus with NH2 as ligand. Full crystallographic information is available from OCA.
Reference
Three-dimensional structure of a gamma-carboxyglutamic acid-containing conotoxin, conantokin G, from the marine snail Conus geographus: the metal-free conformer., Rigby AC, Baleja JD, Furie BC, Furie B, Biochemistry. 1997 Jun 10;36(23):6906-14. PMID:9188685
Page seeded by OCA on Tue Nov 20 10:46:07 2007
