title: Amide proton exchange rates in cardioactive sea anemone polypeptides.
abstract: Amide hydrogen exchange rates have been measured using high-resolution 1H nuclear magnetic resonance (NMR) spectroscopy at 300 MHz for three homologous cardioactive polypeptides, anthopleurin-A from Anthopleura xanthogrammica and Anemonia sulcata toxins I and II. There are approximately 15 slowly exchanging hydrogens in each polypeptide, but the slowest exchange rates are found in ATX II, with ATX I and AP-A having rates similar to one another. The exchange rates correlate with the thermal stability of these molecules, but not with the potency and species specificity of their biological activities. The data for AP-A are interpreted in terms of a recent structural model for this polypeptide.
mesh_terms: D000577:Amides; D000818:Animals; D002316:Cardiotonic Agents; D003063:Cnidaria; D003064:Cnidarian Venoms; D004355:Drug Stability; D036341:Intercellular Signaling Peptides and Proteins; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D010455:Peptides / Q000302:isolation & purification; D011522:Protons; D012615:Sea Anemones
chemical_list: D000577:Amides; D002316:Cardiotonic Agents; D003064:Cnidarian Venoms; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D011522:Protons; C036310:toxin I (Anemonia sulcata); C028800:toxin II (Anemonia sulcata); C012746:anthopleurin-A