Sequential individual resonance assignments in the 1H nuclear-magnetic-resonance spectrum of cardiotoxin VII2 from Naja mossambica mossambica.

The assignment of the 1H nuclear magnetic resonance (NMR) spectrum of cardiotoxin VII2 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 degrees 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 delta amide protons were also identified. For 19 long side chains the individual assignments include only the backbone and C-beta 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 degrees 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 VII2 are in extended, beta-type secondary structures, and there is no indication for the formation of alpha-helical structure.