Determination of the Solution Structures of Conantokin-G and Conantokin-T by CD and NMR Spectroscopy

摘要: Abstract Conantokin-G and conantokin-T are two paralytic polypeptide toxins originally isolated from the venom of fish-hunting cone snails genus Conus. only naturally occurring peptidic compounds which possess N-methyl-D-aspartate receptor antagonist activity, produced by a selective non-competitive antagonism polyamine responses. They also structurally unusual in that they contain disproportionately large number acid labile post-translational γ-carboxyglutamic (Gla) residues. Although no precise structural information has previously been published for these peptides, early spectroscopic measurements have indicated both conantokin-G form α-helical structures, although there is some debate whether presence calcium ions required peptides to adopt this fold. We now report detailed study synthetic range solution conditions using CD 1H NMR spectroscopy. The three-dimensional structures were calculated NMR-derived distance dihedral restraints. Both conantokins found mixture α- 310 helix, give rise curved straight helical conformers. requires divalent cations (Zn2+, Ca2+, Cu2+, or Mg2+) stable α-helix, while adopts structure aqueous conditions, absence Mg2+).