Triglycerides structural analysis

Triglycerides. Structural analysis of the natural fat triglycerides is particularly difiicult because of the many possible molecular species which have very similar chemical and physical properties. Major advances in separation and analytical techniques since 1955 have revolutionized this field. The chemically different triglycerides are now separable by gas-liquid chromatography, by thin-layer chromatography, and/or by permeation chromatography. By use of selective enzymatic deacylation and phosphorylation techniques, the positional isomers can be separated and characterized (121). 

TABLE 3. Structural analysis of the oxidation products of an unsaturated triglyceride (211) with t-BuOOH... 

Jensen, R. G., Sampugna, J. and Pereira, R. L. 1964. Intermolecular specificity of pancreatic lipase and the structural analysis of milk triglycerides. J. Dairy Sci. 47, 727-732,... 

Apolipoprotein C-II can also be isolated from VLDL or HDL (H20, L5, N3). It contains 78 residues (J3) and has been shown by Chou-Fasman analysis to bind phospholipids (M26, M40), with three predicted helical sequences (M26). ApoC-II has attracted a great deal of attention because it activates one of the most important enzymes in plasma lipid metabolism, lipoprotein lipase, responsible for the hydrolysis of triglyceride in chylomicrons and VLDL. Sparrow and Gotto have summarized a number of studies on structure-function relationships (S52). These, taken together, indicate that there are separate functional domains in apoC-II, in that lipoprotein lipase activation is mediated by residues 55-78 and phospholipid binding by... 

Solid Fat Index. This analysis has become the most important criterion for the melting behavior and crystalline structure of fats and oils products. It determines the proportion of solid and liquid materials at a given temperature. The solid fat index (SFI) analysis is an empirical measure of the solid fat content. It is calculated from the specific volume at various temperatures using a dilatometric scale graduated in units of milliliters times 1000. Values for the solid contents are usually determined at 50°F, 70°F, 80°F, 92°F, and 104°F or 10°C, 21.1°C, 26.7°C, 33.3°C, and 40°C. Unlike the tropical oils, cottonseed and the other oleic- and lino-leic-classification oils do not contain any significant quantity of triglycerides made up of two or three saturated fatty acids therefore, the solid fat index at the lowest temperature usually measured would have minimal values. Natural cottonseed oil can have a solid fat index content at 50°F or 10°C but not at the higher temperature measurements. 

Studies of the irfl 5-unsaturation content of fats also provide a good illustration of multicomponent analysis. Naturally occurring vegetable fats and oils are a mixture of triglycerides of the general structure given in Figure 5.6a. 

The analysis of the stereospecific structure of rapeseed oil triglycerides with pancreatic lipase is often accepted as quite straightforward (cf. Breck-enridge, 1979), but in studies with lipases of plant (Rosnitschek and Theimer, 1980), microbial (Kroll et al., 1973) and animal (Myher et al., 1979 Vajreswari and Tulpule, 1980) origins, oils rich in erucic acid tended... 

The average lipid content of the rat heart is about 3% of the fresh weight. The phospholipids comprise 60-70% of the total lipids, the remainder consists of triglycerides (—25%), cholesterol (—6%), cholesteryl ester (—2%) and minor amounts of diglycerides and free fatty acids (Simon and Rouser, 1969 Kramer, 1980). A detailed compositional analysis of the rat heart phospholipids was published by Simon and Rouser (1969) and shown in Table II. The structure of the phospholipids is also given in Table II. 

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