Synthesis of Triglycerides

These finding brought triglyceride synthesis in line with the synthesis of phospholipids, which was shown by Smith et al. (1957) to proceed by removal of the phosphate from phosphatidic acid, with the formation of an a )3-diglyceride. Diglyceride can now be converted into phospholipid, by cytidine-diphosphate-choline or ethanolamine (Kennedy and Weiss 1956) or into neutral triglycerides by the addition of one more fatty acid, derived from fatty acyl-coenzyme A. (Weiss and Kennedy 1956, 1960). 

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The neurohormonal control of lipid metabolism chiefly affects the mobilization and synthesis of triglycerides in the fat tissue. The lipolysis in tissues is dependent upon the activity of triglyceride lipase. All the regulators that favour the conversion of the inactive (nonphosphorylated) lipase to the active (phosphoiylated) one, stimulate the lipolysis and the release of fatty acids into the blood. Adrenalin... 

Mectianism of Action A combination of ethyl esters of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) that inhibits acyl coenzyme A l,2-diacylglycerol acyltransferase and increases peroxisomal oxidation in the liver. Therapeutic Effect Reduces the synthesis of triglycerides in the liver. 

Alterations in the composition of the plasma lipids caused by estrogens are characterized by an increase in the high-density lipoproteins (HDL), a slight reduction in the low-density lipoproteins (LDL), and a reduction in total plasma cholesterol levels. Plasma triglyceride levels are increased. Estrogens decrease hepatic oxidation of adipose tissue lipid to ketones and increase synthesis of triglycerides. 

Glycerol for milk lipid synthesis is obtained in part from hydrolysed blood lipids (free glycerol and monoglycerides), partly from glucose and a little from free blood glycerol. Synthesis of triglycerides within the cell is catalysed by enzymes located on the endoplasmic reticulum, as shown in Figure 3.13. 

Increased synthesis of lipid or uptake. Increased synthesis of lipid may be the cause of fatty liver after hydrazine administration as this compound increases the activity of the enzyme involved in the synthesis of diglycerides. Hydrazine also depletes ATP and, however, inhibits protein synthesis. Large doses of ethanol will cause fatty liver in humans, and it is believed that this is partly due to an increase in fatty acid synthesis. This is a result of an increase in the NADH/NAD"1" ratio and therefore of the synthesis of triglycerides. Changes in the mobilization of lipids in tissues followed by uptake into the liver can also be another cause of steatosis. 

In six patients with renal transplants treated with sirolimus, mean total plasma cholesterol, triglyceride, and apolipoprotein concentrations increased (1067). The authors suggested that sirolimus increases lipase activity in adipose tissue and reduces lipoprotein lipase activity, resulting in increased hepatic synthesis of triglycerides, increased secretion of VLDL, and increased hypertriglyceridemia. 

What is the source of the glycerol molecule that is used in the synthesis of triglycerides ... 

A number of pervaporation membrane bioreactor (PVMBR) applications have also been reported [3.3]. These represent a special class of membrane bioreactor applications, which are discussed more extensively in Chapter 4. A number of studies utilizing PVMBR involve esterification reactions. Van der Padt et al. [3.46], for example, studied in a PVMBR the synthesis of triglycerides from glycerol and fatty acids. The reaction is equilibrium limited, and is described as follows ... 

Experiments carried out with Mucor mucedo (mildew) show that Terrazole inhibits, at the cellular level, the synthesis of triglycerides and sterol esters, stimulates that of free fatty acids and phospholipids,480 but does not appreciably affect nucleic add synthesis.481 Phospholipase is released in cell membranes and mitochondria the associated reduction in mitochondrial... 

The release and utilization of hepatic triglycerides are blocked, although the hepatic synthesis of triglycerides is normal. 

The rate of hepatic synthesis of triglycerides is increased, but utilization is impaired. 

Additional cellular hepatic synthesis of triglycerides occurs other than in the endoplasmic reticulum. 

The quantitative analysis of oxidation of fuels shows that when most carbohydrates are oxidized, the ratio of carbon dioxide produced to oxygen consumed is 1. On the other hand, this ratio, which is called the respiratory quotient (RQ) or the respiratory exchange ratio, is -0.7 when fatty acids are oxidized. The measurements of O2 consumption and CO2 emission only indicate which fuels are being oxidized on average by the whole body and do not necessarily reflect which fuel is being used selectively by particular cell types or tissues. As noted in Chap. 11, the synthesis of triglycerides raises the RQ above 1. 

As mentioned above, lipase-catalyzed synthesis of triglycerides from glycerol and fatty acids can be performed in fair yield in monolayer experiments [93,133]. Another air/water inter facial system, foam, also gave di- and triglycerides in higher yields than were obtained in microemulsions [134]. Reactions in foams may be of more practical interest than reactions in monolayers due to the much larger interfacial area in the former type of system. 

Microemulsion media of low water activity enable hydrolytic enzymes to catalyze condensation as opposed to hydrolysis. This has opened the possibility to perform lipase-catalyzed ester synthesis, an area of considerable practical interest. Lipase-catalyzed transesterification in microemulsion of low water content is another area of industrial relevance, in particular for synthesis of triglycerides with unusual fatty acid composition. 

Describe how amino acids can be used for energy production, the synthesis of triglycerides, and gluconeogenesis. (Section 14.10)... 

A. Koprululu, A. Onen, I. E. Serhatli and F. S. Guner, Synthesis of triglyceride-based urethane macromers and their use in copolymerization . Prog Org Coat, 2008, 63, 365-71. 

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