Sequential individual resonance assignments in the ¹H nuclear-magnetic-resonance spectrum of cardiotoxin V^II 2 from Naja mossambica mossambica

Abstract

The assignment of the ¹H nuclear magnetic resonance (NMR) spectrum of cardiotoxin V^II2 from Naja mossambica mossambica is described and documented. The assignments are based entirely on the amino acid sequence and on two-dimensional NMR experiments at 500 MHz. Individual assignments were obtained at 45 C for the backbone protons of 56 out of the total of 60 amino acid residues, the exceptions being the N-terminal dipeptide segment Leu-1-Lys-2-, Pro-8 and Pro-15. Complete assignments of the non-labile hydrogen atoms of the side chains were obtained for 37 residues, and for Asn-4 and Asn-19 the δ amide protons were also identified. For 19 long side chains the individual assignments include only the backbone and C-β proton resonances; these are Gln-5, Pro-9, Pro-33, Pro-43, Leu-47, all three methionines, two arginines and nine lysines. The chemical shifts for the assigned resonances at 45°C are listed for an aqueous solution at pH 3.6. A preliminary interpretation of the sequential connectivity patterns indicates that approximately 30 out of the total of 60 amino acid residues in cardiotoxin V^II2 are in extended, β-type secondary structures, and there is no indication for the formation of α-helical structure.