Stereospecific analysis of soybean triacylglycerols

Abstract

Thirty soybean germplasm lines representing a wide distribution of fatty acid compositions were analyzed stereospecifically by using a chiral column to resolve the sn-1 and sn-3 positions of glycerol. The amounts of each acyl group on each of the sn positions were plotted vs. the amount of that acyl group in the triacylglycerols (TAG), and the plots were fitted by linear regression. The deviation of individual data points from the linear regressions was much greater than observed in previous studies. This could be attributed to the inclusion of a number of germplasm lines with elevated or reduced percentages of saturates. The stereospecific distributions could not be fit with previously suggested mathematical models because the plots had intercepts that were not allowed by the models. Statistical tests of the analytical procedure indicated that slight oxidation of or bias against the polyunsaturates had occurred and that the Grignard deacylation method gave slightly less representative analyses of the sn-2 position than pancreatic lipase deacylation on these TAG.

Genotype and Growing Environment Effects on the Tocopherols and Fatty Acids of Brassica napus and B. juncea

“…This showed that as the total concentration in oil of a given unsaturated FA increased, its concentration at the sn-2 position also increased. The same relationship has been shown to exist for other oilseeds including soybean [23], maize [24], and Brassica species [25]. The few samples that deviated from this linear relationship had FA compositions markedly different from each other in respect of one or more unsaturated FA.…”

Phospholipid fatty acid composition and stereospecific distribution of soybeans with a wide range of fatty acid composition

“…Similar graphs and linear regression were made. Harper (23) found that there was little saturate at the sn-2 position, and that the slopes of this position for palmitate and stearate were 0.04 and 0.08, as compared with the sums of sn-1 and sn-3 slopes of 2.94 and 2.91. Thus, the sn-2 position palmitate and stearate in PL had greater slopes than in TG.…”

“…It is well documented that saturated fatty acids predominantly occupy the sn-1 and sn-3 positions of soybean TG, and these two positions reflected the saturated fatty acid change in oil (21)(22)(23). Harper (23) used soybean lines that had fatty acid composition ranges similar to those used in this study to analyze acyl group stereospecific distribution in TG.…”

Triacylglycerol profiling by using chromatographic techniques

“…The FA composition of the individual fractions and of the original TGs was determined by GLC and used to calculate the positional distribution on the glycerol backbone. Thirty soybean germplasm lines were analysed stereospecifically [246] by using the chiral column method of Takagi and Ando [243]. On a chiral Sumipax OA-4100 stationary phase an improved resolution of enantiomeric 1,2(2,3)-diacyl-sn-glycerols was obtained [247,248].…”