Fatty acid metabolism in animals

Eight enzyme-catalyzed reactions are involved in the conversion of acetyl-CoA into fatty acids. The first reaction is catalyzed by acetyl-CoA carboxylase and requires ATP. This is the reaction that supplies the energy that drives the biosynthesis of fatty acids. The properties of acetyl-CoA carboxylase are similar to those of pyruvate carboxylase, which is important in the gluconeogenesis pathway (see chapter 12). Both enzymes contain the coenzyme biotin covalently linked to a lysine residue of the protein via its e-amino group. In the last section of this chapter we show that the activity of acetyl-CoA carboxylase plays an important role in the control of fatty acid biosynthesis in animals. Regulation of the first enzyme in a biosynthetic pathway is a strategy widely used in metabolism. 

Liu et al. (2005) have prepared hydrophobic chitosan nanoparticles with linoleic acid for protein delivery. Linoleic acid is an essential fatty acid that exists as a positional and stereoisomer of octa-decadienoic acid, and this type of polyunsaturated fatty acid can sensitize tumour cells to chano-therapy and radiotherapy. This has been proved in cell culture, tumour-bearing animals, and, finally, in humans (Conklin 2002, Germain et al. 1998, Vartak et al. 1997). Linoleic acid plays a mryor role in fatty acid metabolism in the human body. Liu et al. have developed biocompatible amphiphilic lenoleic acid chitosan nanoparticles (100-500 nm), which can be used for protein delivery applications. The loading efficiency decreases with increasing concentration of Bovine Serum Albumin (BSA), and the nanoparticles are saturated with BSA that has a concentration of 0.5mg/mL and a loading capacity of 37.57% 0.25%. BSA forms complexes with a derivative that has a hydrophilic chitosan backbone and a hydrophobic domain of linoleic group. 

Rowley, AE. (1996) The evolution of inflammatory mediators. Mediators Inflamm. 5,3-13 Rowley, A.F., Knight, J., Lloyd-Evans,P., Holland, J.W. and Vickers, P.J. (1995) Eicosanoids and their role in immune modulation in fish - a brief review. Fish Shellfish Immunol. 5,549-567 Henderson, R.J. (1996) Fatty acid metabolism in freshwater fish with particular reference to polyunsaturated fatty acids. Arch. Anim. Nutr. 49,5-22 (extensive review of fatty acid metabolism in fish with some reference to functional aspects)... 

When it was found that two molecules of acetyl CoA participate in the formation of acetoacetate, that acyl phosphates support the oxidation of short-chain fatty acids catalyzed by extracts of Clostridium Muyveri, and that phosphotransacetylase and CoA transphorase were present in these extracts. Barker proposed a scheme of fatty acid oxidation in which acyl CoA compounds served as substrates. The reactions postulated by Barker for the conversion of butyrate to acetyl groups are essenti y those that were subsequently found to participate in fatty acid oxidation in animals and other organisms. With the demonstration that CoA is involved in butyrate metabolism in Clostridium Muyveri, several laboratories simultaneously, independently and successfully studied the role of CoA in fatty acid metabolism. 

Lane, M. D., and Moss, J., 1971, Regulation of fatty acid synthesis in animal tissues, in Metabolic Pathways, Vol. V (D. Greenberg, ed.), p. 23, Academic Press, New York. 

Jorgensen H, Jensen S K and Eggum B O (1996), The influence of rapeseed oil on digestibility, energy metabolism and tissue fatty acid composition in pigs , ActaAgric Scand A Anim Sci, 45, 65-75. 

CONTENTS Acknowledgments, Margery G. Ord and Lloyd A. Stocken. Introduction. Biochemistry Before 1900. Early Metabolic Studies Energy Needs and the Composition of the Diet. Carbohydrate Utilization Glycolysis and Related Activities. Aspects of Carbohydrate Oxidation, Electron Transfer, and Oxidative Phosphorylation. Amino Acid Catabolism in Animals. The Utilization of Fatty Acids. The Impact of Isotopes 1925-1965. Biochemistry and the Cell. Concepts of protein Structure and Function. Chronological Summary of Main Events Up to ca. 1960. Principal Metabolic Pathways. Index. 

Griner RD, Aleo MD, Schnellmann RG (1993), The role of short chain fatty acid substrates in aerobic and glycolytic metabolism in primary cultures of renal proximal tubule cells, In Vitro Cell Dev. Biol. Anim. 29A 649-655. 

Linoleic acid and linolenic acid are essential fatty acids that cannot be made by animals and must be obtained by dietary intake from plant sources. When metabolized in animals, these two acids each give rise to a family of Cig, C20, and C22 n-6 and n-3 polyunsaturated fatty acids thus ... 

Aliphatic EC>16-EC35 Fraction. Aliphatic hydrocarbons in this fraction are not expected to undergo extensive metabolism in animals or humans. In monkeys, 2 days after intramuscular injection of a mineral oil emulsion with a radiolabeled C16 hydrocarbon Oz-hexanedecane), substantial portions (30-90%) of radioactivity in various tissues existed as unmetabolized n-hexanedecane. The remainder of the radioactivity was found as phospholipids, free fatty acids, triglycerides, and sterol esters. No radioactivity was found in water-soluble fractions (ATSDR 1997b). The common presence of lipogranulomata in human autopsies and the widespread dietary exposure to mineral oils and waxes (Wanless and Geddie 1985) are consistent with the concept that aliphatic hydrocarbons in this fraction are slowly metabolized. 

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