A novel chemical synthesis of 1-O-hexadecyl-rac-[2-3H]glycero-3-phosphorylethanolamine and a simple assay for plasmanyl desaturase

A simple and efficient method for chemical synthesis of lysophosphatidylethanolamine is described. 1-O-hexadecyl diazohydroxyacetone (A. K. Hajra, T. V. Saraswathi and A. K. Das. 1983. Chem. Phys. Lipids. 33: 179-193) was decomposed by benzyloxycarbonyl (CBZ) derivative of phosphorylethanolamine (I) to give 1-O-hexadecyl dihydroxyacetone-3-(N)-CBZ phosphorylethanolamine (II). Compound (II) was reduced by NaBH4 and the product (III), after catalytic transfer hydrogenolysis produced the final compound, 1-O-hexadecyl-rac-glycero-3-phosphorylethanolamine (IV). The yield of (IV), starting from 1-O-hexadecyl diazohydroxyacetone was 53%. The identities of the compounds were verified by NMR and fast atom bombardment mass spectral (FAB-MS) analysis. 1-O-hexadecyl-rac[2-3H]glycero-3-phosphorylethanolamine prepared by the method above was shown to be a good in vitro substrate for plasmanyl delta 1'-desaturase (EC 1.14.99.19). Using this radioactive substrate, a simple and rapid solvent partition assay for this enzyme was developed with results comparable to those obtained by the two-dimensional thin-layer chromatographic assay method. The advantage of this rapid assay system and the applicability of the chemical synthetic method for other phosphoglycerides are discussed.