title: Characterization of 9H-(1,3-dichlor-9, 9-dimethylacridin-2-ona-7-yl)-phosphate (DDAO) as substrate of PP-2A in a fluorimetric microplate assay for diarrhetic shellfish toxins (DSP).
abstract: Specific inhibition of protein-phosphatases by diarrhetic shellfish toxins (DSP) of the okadaic acid group, has led to the development of a fluorescent enzyme inhibition assay for these toxins using protein-phosphatase 2A (PP-2A) and fluorogenic substrates of the enzyme. Two different substrates of PP-2A have been previously used in this microplate assay: 4-methylumbelliferyl phosphate and fluorescein diphosphate (FDP). In this report, we present the results obtained using a new fluorogenic substrate of PP-2A, the compound dimethylacridinone phosphate (DDAO). A linear relationship between PP-2A concentration and DDAO-induced fluorescence was observed. Okadaic acid (0.0157-9.43 nM)-dependent inhibition of phosphatase activity showed similar results using FDP and DDAO. Recovery percentages obtained with FDP and DDAO in spiked mussel samples (both raw and canned) were very similar and reproducible. Comparative analysis of DSP-contaminated mussel samples by HPLC and FDP/DDAO-PP-2A showed a good correlation among all methods, thus demonstrating that DDAO can be used as a fluorogenic substrate to quantify okadaic acid and related toxins in bivalve molluscs with optimum reliability.
authors.affiliation: ANFACO-CECOPESCA, Campus Universitario de Vigo, Spain. fleira@anfaco.cesga.es
authors.forename: F
authors.initials: F
authors.lastname: Leira
authors.forename: J M
authors.initials: JM
authors.lastname: Vieites
authors.forename: M R
authors.initials: MR
authors.lastname: Vieytes
authors.forename: L M
authors.initials: LM
authors.lastname: Botana
mesh_terms: D000166:Acridines / Q000494:pharmacology*; D000818:Animals; D049872:Bivalvia / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019793:Fluorescein / Q000378:metabolism; D005470:Fluorometry / Q000379:methods*; D006923:Hymecromone / Q000031:analogs & derivatives* / Q000378:metabolism; D007202:Indicators and Reagents / Q000378:metabolism; D008387:Marine Toxins / Q000032:analysis* / Q000378:metabolism / Q000494:pharmacology; D019319:Okadaic Acid / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000737:chemistry*; D015203:Reproducibility of Results; D012758:Shellfish; D013379:Substrate Specificity
chemical_list: C416725:9H-(1,3-dichloro-9,9-dimethylacridine-2-on-7-yl)phosphate; D000166:Acridines; D004791:Enzyme Inhibitors; D007202:Indicators and Reagents; D008387:Marine Toxins; D019319:Okadaic Acid; C005359:4-methylumbelliferyl phosphate; D006923:Hymecromone; D010749:Phosphoprotein Phosphatases; D019793:Fluorescein