okadaic-acid and 6-carboxyfluorescein

Okadaic acid (OKA), a marine toxin produced by dinoflagellates, is responsible for most human diarrhetic shellfish poisoning-associated health disorders. A competitive displacement assay for OKA is described here. An OKA-binding aptamer was truncated with two sequences, one labeled with 6-carboxyfluorescein (FAM), and one with a quencher. On addition of OKA, it will bind to the aptamer and green fluorescence pops up because label and quencher become spatially separated. One of the truncated aptamers exhibis an excellent binding capability (Kd 2.77 nM) for OKA compared to its full-length aptamer (526 nM). The selectivity of the assay was proven by the successful fluorometric determination of OKA in the presence of common diarrhoetic toxins and in shellfish extracts. The detection limit is as low as 39 pg·mL

Topics: Aptamers, Nucleotide; Biosensing Techniques; Complex Mixtures; Fluoresceins; Fluorescent Dyes; Fluorometry; Gold; Limit of Detection; Marine Toxins; Metal Nanoparticles; Okadaic Acid; Shellfish

The interaction of okadaic acid (OA) with lipid bilayer membranes was studied to obtain information on its incorporation into the target cell. OA, which possesses a polyether structure with a carboxylic acid, was extracted with a chloroform or n-octanol solution from a buffer solution, indicating the hydrophobicity of OA. However, the distribution of OA to dipalmitoylphosphatidylcholine membrane was so low that OA did not strongly induce perturbation in the membrane structure. On the other hand, OA permeated freely through the lipid membrane in a liquid-crystalline state. It was therefore suggested that OA permeates through cell membrane and binds to the receptor, for example, protein phosphatase, which exists either in the cytosol or in the cell membrane.

Topics: 1,2-Dipalmitoylphosphatidylcholine; Buffers; Cell Membrane Permeability; Ethers, Cyclic; Fluoresceins; Membrane Fluidity; Membrane Lipids; Okadaic Acid; Spectrum Analysis; Tetradecanoylphorbol Acetate