The NMR solution structure of the NMDA receptor antagonist, conantokin‐T, in the absence of divalent metal ions

FEBS Letters

Warder, Scott E¹  Chen, Zhigang²  Ni, Feng²  Zhu, Yi²  Prorok, Mary¹  Castellino, Francis J¹ 

[1] Department of Chemistry and Biochemistry and the Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA;Biomolecular NMR Laboratory and the Montreal Joint Centre for Structural Biology, Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, Montreal, Quebec H4P 2R2, Canada

关键词: Conantokin-T;    Peptide folding;    NMDA receptor;    Helical polypeptides;    gamma-Carboxyglutamate;   

DOI  :  10.1016/S0014-5793(97)00573-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The solution conformation of conantokin-T, a Gla-containing 21-residue peptide, (G₁EγγY₅QKMLγ₁₀NLRγA₁₅EVKKN₂₀A-amide), in the absence of divalent metal ions, was studied by use of two-dimensional proton NMR spectroscopy. The peptide is helical from the N-terminus to the C-terminus, as defined by upfield-shifted α-proton resonances and by characteristic NOE connectivities. Extensive interactions among the amino acid side-chains were identified from the NOESY spectra of this peptide in a buffered aqueous solution. Four hydrophobic residues Tyr⁵, Met⁸, Leu⁹, and Leu¹² contact one another in a stable cluster, even in the presence of 6 M urea. The solution structure of conantokin-T is a well-defined α-helix, having RMSD values for the backbone and all heavy atoms of 0.40 Å and 0.77 Å, respectively. Potential repulsion between the negatively-charged side chains of Gla¹⁰ and Gla¹⁴ is minimized by a Gln⁶-Gla¹⁰ hydrogen bond and by an Arg¹³-Gla¹⁴ ion-pair interaction. The C-terminal amide and the Asn²⁰ side-chain amide both interact with the backbone and minimize fraying at the C-terminal end of the α-helix. This study provides a basis to evaluate the changes in peptide conformation concomitant upon the binding of divalent metal ions. In addition, this investigation demonstrates that apo-conantokin-T has almost all of the favorable interactions that are known to contribute to helical stabilization in proteins and monomeric helices.

【 授权许可】

Unknown