title: Identification of palytoxin-Ca2+ complex by NMR and molecular modeling techniques.
abstract: More than 40 years after its isolation, the understanding of how palytoxin interacts with biological systems has yet to be fully determined. The Na(+),K(+)-ATPase pump constitutes a molecular receptor for palytoxin that is able to convert the pump into an open channel, with consequent loss of cellular K(+) and remarkable rise of cytosolic Na(+) levels. In addition, a slight permeability to Ca(2+) is detected when palytoxin binds to the pump. It has been demonstrated that the increase of cytosolic free Ca(2+) concentration gives rise to downstream events ultimately leading to cell death. The widely accepted recognition of the dependence of important cellular events on calcium ion concentration propelled us to investigate the occurrence of palytoxin-Ca(2+) complex in aqueous solution by NMR- and molecular modeling-based approach. We identified two specific regions of palytoxin where Ca(2+) is preferentially coordinated. This study constitutes the first characterization of a calcium complex with palytoxin and, as such, is expected to support the investigation of the toxin molecular bioactivity.
authors: Department of Pharmacy, University of Napoli "Federico II" , Italy Via D. Montesano, 49-80131 Napoli, Italy.
authors: Patrizia
authors: P
authors: Ciminiello
authors: Carmela
authors: C
authors: Dell'Aversano
authors: Emma
authors: E
authors: Dello Iacovo
authors: Martino
authors: M
authors: Forino
authors: Antonio
authors: A
authors: Randazzo
authors: Luciana
authors: L
authors: Tartaglione
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry*; D002412:Cations / Q000737:chemistry*; D003064:Cnidarian Venoms; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry* / Q000378:metabolism; D000095702:Polyether Toxins
chemical_list: D000178:Acrylamides; D002118:Calcium; D002412:Cations; D003064:Cnidarian Venoms; D000254:Sodium-Potassium-Exchanging ATPase; C010272:palytoxin; D000095702:Polyether Toxins