Isolation and identification of 1(3),2-diacylglyceryl-(3)-O-4'-(N,N,N-trimethyl)homoserine from the soil amoeba, Acanthamoeba castellanii.

A polar lipid accounting for 12.5% of the total lipid nitrogen has been isolated from the protozoan Acanthamoeba castellanii. On the basis of thin-layer chromatography and mass spectral analysis, the lipid has been identified as diacylglyceryltrimethylhomoserine (DGTS). Fast atom bombardment (FAB) mass spectra of DGTS are reported for the first time and are compared to the FAB mass spectra of phosphatidylcholines and the electron ionization (EI) and field desorption (FD) mass spectra of DGTS. Gas-liquid chromatographic-mass spectrometric (GLC-MS) analysis of the acyl chain composition of this lipid has shown that 87.5% consists of cis-9-octadecenoic acid. Plasma membrane isolated from this organism has shown that labeled DGTS appears in the plasma membrane but is not enriched in this fraction. DGTS has been isolated previously only from a limited number of green plants and one species of fungus. Identification of this lipid in Acanthamoeba indicates that this lipid is distributed among a diverse group of lower eucaryotes.