The
triacylglycerols of
very low density lipoproteins (VLDL-TG) were analyzed in samples from normal subjects and patients with Frederickson's Type III and
Type IV hyperlipoproteinemia. VLDL were obtained by conventional ultracentrifugation, and the
triacylglycerols were isolated by thin-layer chromatography (TLC). Representative sn-1,2(2,3)- and sn-1,3-diacylglycerols were generated by Grignard degradation of the
triacylglycerols, and were resolved by TLC on
borate-treated
silica gel. The molecular association of the
fatty acids in the
diacylglycerol moieties was determined by gas-liquid chromatography with mass spectrometry (GC/MS) of the tertiary-butyldimethylsilyl
ethers. The positional distribution of the
fatty acids was established by the Brockerhoff stereospecific analysis. The results showed a marked asymmetry in the distribution of the
fatty acids in all samples, with the saturated
acids predominantly in the sn-1-position and the
unsaturated fatty acids distributed about equally between the sn-2- and sn-3-positions. In all instances, the molecular species composition of the sn-1,2-, sn-2,3- and sn-1,3-diacylglycerols was found to be similar to that calculated for 1-random 2-random 3-random distribution of
triacylglycerols. There were marked differences in the quantitative composition of the molecular species of the VLDL-TG between normal subjects and patients, but these discrepancies were attributed to differences in the
fatty acid composition of the samples.