A PROTEIN PHOSPHATASE 2A INHIBITION ASSAY FOR A FAST AND SENSITIVE ASSESSMENT OF OKADAIC ACID CONTAMINATION IN MUSSELS

The specific inhibitory activity exerted by okadaic acid on protein ph osphatase 2A was used to assess the presence of okadaic acid in mussel s, using a commercially available protein phosphatase 2A preparation. Under the conditions used, okadaic acid inhibits the enzymatic activit y dose-dependently, with an IC50 = 0.26 ng/ml (0.32 nM). The assay is accurate and reproducible. Okadaic acid was detected in concentrations as low as 0.063 ng/ml in aqueous solutions acid 2 ng/g in mussel dige stive glands. Thirty naturally contaminated mussel samples were submit ted to the protein phosphatase 2A inhibition assay as well as to an EL ISA assay and to a MTT cytotoxicity assay, with similar results. The p roposed assay is sensitive, rapid and does not require expensive equip ment. These characteristics make it a good candidate for employment in the routine assessment of okadaic acid shellfish contamination. Copyr ight (C) 1996 Elsevier Science Ltd