J. Biochem, 1996, Vol. 119, No. 4 823-827
© 1996 Japanese Biochemical Society
research-article |
Isolation, Chemical Characterization, and Subcellular Distribution of 1-O-Alkyl-2-Acetyl-sn-Glycerol in Tetrahymena pyriformis Cells1
Laboratory of Biochemistry, Department of Chemistry, University of Ioannina 45110 Ioannina, Greece
2To whom correspondence should be addressed. Tel: +30651-98367, Fax:+30651-47832, e-mail: mlekka{at}c.c.uoi.gr
1-O-Hexadecyl-2-acetyl-sn-glycerol, the immediate precursor of platelet-activating factor (PAF) in itsde novo formation,was detected in the protozoon Tetrahymena pyriformis. It was purified from the total lipid extract by TLC, after successive developments in two different solvent systems. Characterization was assessed by (a)gas-liquid chromatography with electron capture detection, and (b)gas chromatography combined with mass spectrometry in selected ion monitoring mode, after derivatization with heptafluorobutyric acid anhydride and teri-butyldimethylchlorosilane/imidazole, respectively. Its quantity was found to be 0.1 nmol/107cells from the GC-MS, using authentic alkylacetylglycerol as external standard. Cell fractionation revealed that alkylacetylglycerol is located exclusively in the microsomal fraction of the protozoon.Previously, we have reported the occurrence of PAF in the microsomal fraction, as well as a dithiothreitol-insensitive CDP-choline: cholinephosphotransferase activity that utilizes exogenous alkylacetylglycerol as substrate in the mitochondrial and microsomal fractions. The above findings indicate that PAF can be formed in the cell by the de novo pathway.