Synthesis and characterization of a new fluorescent phospholipid

A novel fluorescent phospholipid was synthesized by the reaction of 0-phthalaldehyde and β-mercaptoethanol with phosphatidylethanolamine. Its structure had been tentatively assigned as 1-(2’-yhio-1'-hydroxyethyl)-2-(ethyl-phosphatidyl)-isoindole (THEPI). The fluorescent lipid product was purified by solvent extraction and silicic acid chromatography. The purity was demonstrated by thin layer chromatography. This fluorescent phospholipid could not form stable unilamellar lipid vesicles. However, it does so together with phosphatidylcholine after sonication, as shown by Sepharose 4B column chromatography and electron microscopy. The optimal properties of this lipid, in the form of aqueous micelles and after incorporated into vesicles, have been determined. The potential use of this new fluorescent phospholipid in membrane studies is discussed.