Metal cations for the determination of fluorescent phosphoinositides by capillary electrophoresis

Phosphatidylinositol (PI) and its phosphorylated derivatives known as phosphoinositides (PIPs), are essential regulators of cell signaling and membrane trafficking, cytoskeletal dynamics, and nuclear functions. Disruption of PI metabolism is associated with disorders such as immune dysfunction, cardiovascular disease, and cancer; therefore, there is currently great interest in studying PIPs and their metabolic enzymes. Here, we describe a method for the separation of fluorescent PI and its seven fluorescent phosphorylated derivatives by CE-LIF. The CE method utilizes a Tris buffer and sodium deoxycholate in the presence of 30% 1-propanol and 5% of a dynamic coating reagent, EOTrol low reverse (EOTrol LR). It is simple, fast, highly sensitive, and it offers LODs in the order of 1.5 amol. The effect of cations such as lithium, sodium, potassium, cesium, barium, manganese, zinc, magnesium, calcium, spermine, and gentamicin were evaluated. Calcium and magnesium provided the best selectivity and resolution for the separation of the analytes while magnesium offered the best data reproducibility. The developed CE method would be useful in the studies of enzymatic activity in the PI and PIPs metabolic pathways using CE-based in vitro and CE cell-based assays, and/or for drug screening.