Triglycerides biosynthesis

Triglyceride biosynthesis proceeds with the involvement of the lipids deposited in fat tissue or in other tissues of the organism. This process is localized in the hyaloplasm of cells. 

The first step of triglyceride biosynthesis is the formation of phosphatidic acid with the involvement of glycerophosphate acyltrans-ferase ... 

Ceriani, R. L., Peterson, J. A., Lee, J. Y., Moncada, R. and Blank, E. W. 1983. Characterization of cell surface antigens of human mammary epithelial cells with monoclonal antibodies prepared against human milk fat globule. Somat. Cell Genet. 9, 415-427. Christie, W. W. and Wooding, F. B. P. 1975. The site of triglyceride biosynthesis in milk. Experientia 31, 1445-1447. 

Glycerol-3-phosphate is a triglyceride biosynthesis intermediate (see Chapter 19), as well as a means of transporting electrons into the mitochondria. Remem-... 

Know pathways of triglyceride biosynthesis and catabolism, the /3-oxidative pathway, and pathways for the degradation of pro-pionyl-CoA, branched fatty acids, and unsaturated fatty acids identify cofactors required calculate ATP yields for fatty acid oxidation know the identity of key enzymes in each pathway. 

Fatty acids released by lipoprotein lipase are taken up by the tissue where this enzyme is located, where they may be oxidized (see later) or stored in the form of triglycerides, such as adipose tissue. Triglyceride biosynthetic enzymes are located in the endoplasmic reticulum. Triglyceride biosynthesis is summarized in Figure 19.4. It is seen that dihydroxyacetone phosphate (see Chapter 18) is a key intermediate. It can combine with an acyl residue carried by acyl coenzyme A... 

In human adipose tissue, palmitoyl-CoA is usually used in the first glycerol-3-phosphate acylation reaction. The next two acyl residues are normally unsaturated fatty acids oleic acid and, less commonly, linoleic acid. Triglyceride biosynthesis is stimulated by insulin, most likely via its activation of lipoprotein lipase and its activity in moving glucose into the cells. 

Phosphoglycerides may be synthesized either from phosphatidic add or by the so-called salvage pathway. Phosphatidic acid is also an intermediate in triglyceride biosynthesis (Figure 19.4). The phosphatidic acid pathway is relatively minor in eukaryotes phosphatidic acid reacts with CTP to form CDP diglyceride (see Figure 19.15), and the latter may then react with choline or inositol to form phosphatidylinositol or phosphatidylcholine, as in Equations (19.14) and (19.15). 

D. Steinberg, M. Vaughan, and S. Margolis, Studies of triglyceride biosynthesis in homogenates of adipose tissue,/. Biol. Chem., 1961, 236, 1631-1637. 

Gurr, M. I., Blades, J., Appleby, R. S.,Smith, C. G., Robinson, M. P., Nichols, B. W. (1974) Studies on seed oil triglycerides. Triglyceride biosynthesis and storage in whole seeds and oil bodies of Crambe abyssinica. 

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