Triacylglycerols mobilization

Hormone-sensitive lipase PMRRSV Triacylglycerol mobilization and fatty acid oxidation... 

Glucagon also raises cAMP levels in adipose tissue. There the chief effect of cAMP is to promote triacylglycerol mobilization via phosphorylation of hormone-sensitive lipase, yielding glycerol and fatty acids. 

The pathways for liberation of fatty acids from triacylglycerols, either from adipose cells or from the diet, are shown in Figures 24.2 and 24.3. Fatty acids are mobilized from adipocytes in response to hormone messengers such as adren-... 

Nova-Pak C18 column in a methanol water chloroform gradient.92 Choline chloride was added to the mobile phase. One review of techniques used in the analysis of triacylglycerols lists over 300 references on separations of the triglyceride fraction of fats using nonaqueous RPLC, aqueous RPLC, argen-tation chromatography, and other chromatographic methods.93... 

The factors affecting Rf include the quality of the stationary and mobile phases, the thickness and activity of the layer, and the amount of sample. Although standards may have the same Rf value as the sample, this does not uniquely identify the compound. For archaeological samples, the best identification achievable is only at a general class level (e.g., triacylglycerols, fatty acids, aromatic, or aliphatic) and not to individual molecular components. 

Various combinations of hexane or light petroleum (40-60°C, bp) and diethyl ether, usually with a small amount of acetic acid (e.g. 90 10 1) or diisopropyl ether and acetic acid (98.5 1.5) are commonly used. The greater mobility is demonstrated by cholesterol esters followed by triacylglycerols, free fatty acids, cholestorol, diacylglycerols and monoacylglycerols, with complex polar lipids remaining unmoved. Double development in two solvents, e.g. diisopropyl... 

Chylomicrons deliver tiiacylglycerols to tissues, where lipoprotein lipase releases free fatty acids for entry into cells. Triacylglycerols stored in adipose tissue are mobilized by a hormone-sensitive triacylglycerol lipase. The released fatty acids bind to serum albumin and are carried in the blood to the heart, skeletal muscle, and other tissues that use fatty acids for fuel. 

Fatty acids are carried to tissues for use in synthesis of triacylglycerols, phospholipids, and other membrane lipids. The mobilization of fatty acids from triacylglycerol stores and from cholesterol esters depends upon hormone-sensitive lipase (p. 635).53b/ 53c This enzyme is activated by cAMP-dependent phos-... 

Such solvent systems continued to be used even though the lack of solubility of triacyl-glycerols with carbon numbers greater than 46 in this mobile phase has been noted. The solvent gradients that would be required for optimum separations of complex triacylglycerol mixtures are not compatible with RI detection. Therefore, ultraviolet detectors have also been used, but the range of mobile phases is limited, since TGs absorb only in the far-UV range. 

Fig. 30 Silver ion high-performance liquid chromatography (Ag-HPLC-FID) with flame ionization detector (FID) analysis of the triacylglycerols of chromatographed Crepis alpina seed oil. Ag-HPLC-FID conditions 0.5-mg sample 5-micron Chromspher Lipids column (Chrompack International, Middelburg, The Netherlands) (4.6 X 250 mm) mobile phase 0.5% acetonitrile in hexane (v/v) flow rate 1.0 ml/min FID. Chromatogram peak triacylglycerol fatty acid abbreviations S, saturated (palmitic and stearic) O, oleic L, linoleic and Cr, crepenynoic fatty acids.

Fig. 41 Separation of triacylglycerols on Supelcosil-LC 8 with acetone-acetonitrile (70 30, v/v) as the mobile phase and refractive index detection. Flow rate, 1.0 ml/min. (a) Olive oil, (b) soybean oil, (c) sunflower oil, (d) corn oil.

Under conditions of nutritional excess, fatty acids are absorbed by adipose tissue where they are converted to storage lipids in the form of triacylglycerols. The triacylglycerols can be mobilized at a later time, when the carbohydrate... 

Figure 32-3. Schematic representation of fuel mobilization during fasting. Catabolism of muscle proteins provides alanine for gluconeogenesis and glutamine for utilization by the gut and kidney, while branched chain amino acids are primarily oxidized within the muscle. Breakdown of adipocyte triacylglycerols provides glycerol and free fatty acids (not shown) the free fatty acids provide fuel for liver, muscle and most other peripheral tissues. The liver utilizes both alanine and glycerol to synthesize glucose which is required for the brain and for red blood cells (not shown). Adapted from Besser and Thirner (2002).

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