Affinity capillary electrophoresis for screening proteins interacting with domoic acid

Abstract

Domoic acid (DA) is a biological neurotoxin that causes amnesic shellfish poisoning. Study of the interactions between DA and important functional proteins contributes to understand the toxicity mechanism of DA to biological macromolecules. In this paper, the interactions between DA and nine important proteins in plasma, intestine and mitochondria were qualitatively compared by affinity capillary electrophoresis. Proteins were used as affinity ligands while DA as the affinity receptor. Proteins with the concentrations of 0, 0.2, 0.4, 0.6, 0.8 μmol/L were added in the electrophoresis buffer and the migration times of 0.2 mg/mL DA were detected. Then the linear graphs of the variation of DA mobility ratio (ΔM) with the protein mass concentration (L) were drawn. According to the slope value, the relative strength of the interactions between DA and proteins was compared. The results showed that six proteins can interact with DA and the relative strength order was human thrombin > cytochrome C trypsin immunoglobulin E (Ig E) ≈ ribonuclease A > λ exonuclease, while ferritin, transferrin and lectin had no affinity with DA. With the advantages of high efficiency, fast analysis and less sample consumption, affinity capillary electrophoresis is a convenient method for screening DA target proteins, which will provide basic information for the toxic mechanism and defence of DA.