Secondary structure determination for α‐neurotoxin from Dendroaspis polylepis polylepis based on sequence‐specific 1H‐nuclear‐magnetic‐resonance assignments

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Abstract
Sequence-specific assignments are presented for the polypeptide backbone protons and a majority of the amino-acid-side-chain protons of α-neurotoxin from Dendroaspis polylepis polylepis, and individual amide proton-exchange rates with the solvent are reported. The secondary structure and the hydrogen-bonding patterns in the regular secondary structure elements are deduced from nuclear Overhauser effects and the sequence locations of the slowly exchanging amide protons. The molecule includes a three-stranded antiparallel β-sheet, and there are indications that two additional short chain segments are arranged in an antiparallel β-sheet. These structural elements are similar, but not identical, to either the secondary structure reported for erabutoxin b in single crystals, or the solution structure of cytotoxin CTXIIb from Naja mossambica mossambica.