Development of an efficient protein phosphatase-based colorimetric test for okadaic acid detection

Area of Science:

• Biochemistry
• Analytical Chemistry
• Food Safety

Background:

• Okadaic acid (OA) is a marine toxin causing gastrointestinal illness.
• OA inhibits protein phosphatase 2A (PP2A), presenting a potential detection mechanism.
• Accurate and sensitive detection of OA is crucial for public health and food safety.

Purpose of the Study:

• To develop and optimize an assay for detecting okadaic acid (OA).
• To evaluate different sources of protein phosphatase 2A (PP2A) for assay performance.
• To compare the efficacy of soluble versus immobilized PP2A in polymeric matrices for OA detection.

Main Methods:

• Tested three sources of PP2A: two commercial and one engineered.
• Assayed PP2A activity in solution and immobilized within photopolymer and agarose gel matrices.
• Determined detection limits and IC50 values for OA using optimized assay conditions.

Main Results:

• PP2A from ZEU Immunotec demonstrated superior performance in solution, with a detection limit of 0.0124 μg L⁻¹ for OA.
• Immobilization of PP2A in agarose gel enhanced stability and sensitivity, achieving an IC50 of 1.98 μg L⁻¹.
• The agarose gel matrix provided a 1.8-fold improvement over the photopolymer matrix.

Conclusions:

• An optimized PP2A inhibition assay, particularly with PP2A immobilized in agarose gel, provides a sensitive, rapid, and cost-effective method for OA detection.
• The assay is effective for detecting OA in both aqueous solutions and contaminated shellfish.
• This method offers a valuable tool for monitoring OA contamination and ensuring food safety.