Conformational heterogeneity in polypeptide cardiac stimulants from sea anemones

Paul R. Gooley, John W. Blunt, Raymond S. Norton

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High-resolution 1H NMR spectra at 300 MHz of the polypeptide cardiac stimulants anthopIeurin-A and Anemonia sulcata toxin II reveal conformational heterogeneity in both molecules. The two conformations, manifest in a number of split 1H resonances, are in slow exchange over a wide range of pH and temperature. Heterogeneity affects a region of these molecules containing the structurally and functionally important Asp residues. By comparison with a homologous polypeptide Anemonia sulcata toxin I, which does not show this type of heterogeneity, it is suggested that the heterogeneity may originate in cis-trans isomerism of the Gly-40 to Pro-41 peptide bond.

Original languageEnglish
Pages (from-to)15-19
Number of pages5
JournalFEBS Letters
Issue number1
Publication statusPublished - 20 Aug 1984
Externally publishedYes


  • H-NMR
  • Cardiotonic agent
  • Neurotoxin
  • Peptide conformation
  • pH titration
  • Proline

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