title: Brevetoxin binding: molecular pharmacology versus immunoassay.
abstract: Brevetoxin PbTx-3 isolated from Florida's red tide dinoflagellate Ptychodiscus brevis has been produced recently in tritiated form by reductive tritiation of brevetoxin PbTx-2. Tritiated PbTx-3 has been used as a specific probe in competitive radioimmunoassays developed to detect brevetoxins in food sources, and this probe has also been utilized to characterize the brevetoxin binding component in rat brain synaptosomes. Brevetoxins PbTx-2 and PbTx-3, possessing the same structural backbone (type-1) as the tritiated probe, and PbTx-1 and PbTx-7, possessing a second structural backbone (type-2), have been compared quantitatively in their individual abilities to competitively displace tritiated PbTx-3 from its specific binding site in each assay. Type-1 toxins displaced labeled probe with ED50 values of 20-22 nM and 12-17 nM in radioimmunoassay and synaptosomes, respectively. Type-2 toxins displaced labeled probe with ED50 values of 92-93 nM and 3.5-4.1 nM in RIA and synaptosomes, respectively. Synaptosome assays reflect potency of each toxin examined, while radioimmunoassay reflects structural similarities to the immunizing toxin PbTx-3.
authors.affiliation: University of Miami, Rosenstiel School of Marine and Atmospheric Science, Division of Biology and Living Resources, Florida 33149.
authors.forename: D G
authors.initials: DG
authors.lastname: Baden
authors.forename: T J
authors.initials: TJ
authors.lastname: Mende
authors.forename: A M
authors.initials: AM
authors.lastname: Szmant
authors.forename: V L
authors.initials: VL
authors.lastname: Trainer
authors.forename: R A
authors.initials: RA
authors.lastname: Edwards
authors.forename: L E
authors.initials: LE
authors.lastname: Roszell
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism; D003532:Cyprinodontiformes / Q000502:physiology; D006041:Goats / Q000276:immunology; D007118:Immunoassay; D066298:In Vitro Techniques; D008297:Male; D008387:Marine Toxins / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D035964:Oxocins; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000378:metabolism; D000095702:Polyether Toxins
chemical_list: D008387:Marine Toxins; D035964:Oxocins; C053342:brevetoxin; D000095702:Polyether Toxins