Fatty acids synthetase

We can descnbe the major elements of fatty acid biosynthesis by considering the for mation of butanoic acid from two molecules of acetyl coenzyme A The machinery responsible for accomplishing this conversion is a complex of enzymes known as fatty acid synthetase Certain portions of this complex referred to as acyl carrier protein (ACP), bear a side chain that is structurally similar to coenzyme A An important early step m fatty acid biosynthesis is the transfer of the acetyl group from a molecule of acetyl coenzyme A to the sulfhydryl group of acyl carrier protein... 

Fatty acid synthetase (Section 26 3) Complex of enzymes that catalyzes the biosynthesis of fatty acids from acetate Field effect (Section 19 6) An electronic effect in a molecule that IS transmitted from a substituent to a reaction site via the medium (e g solvent)... 

Biosynthesis of coen2yme A (CoA) ia mammalian cells incorporates pantothenic acid. Coen2yme A, an acyl group carrier, is a cofactor for various en2ymatic reactions and serves as either a hydrogen donor or an acceptor. Pantothenic acid is also a stmctural component of acyl carrier protein (AGP). AGP is an essential component of the fatty acid synthetase complex, and is therefore requited for fatty acid synthesis. Free pantothenic acid is isolated from hver, and is a pale yeUow, viscous, and hygroscopic oil. 

Fatty acid synthetase (Section 26.3) Complex of enzymes that catalyzes the biosynthesis of fatty acids from acetate. 

In the organism tissues, fatty acids are continually renewed in order to provide not only for the energy requirements, but also for the synthesis of multicomponent lipids (triacylglycerides, phospholipids, etc.). In the organism cells, fatty acids are resynthetized from simpler compounds through the aid of a supramolecular multienzyme complex referred to as fatty acid synthetase. At the Lynen laboratory, this synthetase was first isolated from yeast and then from the liver of birds and mammals. Since in mammals palmitic acid in this process is a major product, this multienzyme complex is also called palmitate synthetase. 

The key enzymes involved in the biosynthetic pathways of the Type I compounds are the fatty acid synthesis enzymes acetyl-CoA carboxylase and fatty acid synthetase. These enzymes are similar to those that produce the normal fatty acids used by all organisms. The resulting products are palmitic (16 car-... 

Specific chain length fatty acids could be produced in two ways. One is through the action of a thioester hydrolase that interacts with fatty acid synthetase to produce fatty acids shorter in length. Aphids produce myristic acid (14 carbons) and a specific thioester hydrolase releases the fatty acid from fatty acid synthetase after 6 additions of malonyl-CoA. If the hydrolase is not present then the fatty acid synthetase produces stearic acid [27]. A specific thioester hydrolase was ruled out in the biosynthesis of moth sex pheromones because labeling studies showed that longer chain length fatty acids were incorporated into shorter chain length pheromone components [22,28]. 

NADP+ [EC 1.3.1.10] to produce 2,3-dehydroacyl-[acyl-carrier-protein] and NADH or NADPH. See also Fatty Acid Synthetase... 

This enzyme, officially known as 3-hydroxypalmitoyl-[acyl-carrier protein] dehydratase [EC 4.2.1.61], is the fatty-acid synthase component that catalyzes the conversion of (3 i )-3-hydroxypalmitoyl-[acyl-carrier protein] to form 2-hexadecenoyl-[acyl-carrier protein] and water. This enzyme displays specificity toward 3-hydroxyacyl-[acyl-carrier protein] derivatives (with chain lengths from Ci2 to Cie), with highest activity on the palmitoyl derivative. See also Fatty Acid Synthetase... 

This enzyme [EC 2.3.1.41], also known as 3-oxoacyl-[acyl-carrier protein] synthase, catalyzes the reaction of an acyl-[acyl-carrier protein] with malonyl-[acyl-carrier protein] to produce a 3-oxoacyl-[acyl-carrier protein], carbon dioxide, and the [acyl-carrier protein]. See also Fatty Acid Synthetase... 

FATTY ACID SYNTHETASE /3-KETOACYL-ACP SYNTHASE FATTY ACID SYNTHETASE a-KETOBUTYRATE SYNTHASE 2-Keto-3-deoxy-L-arabonate aldolase,... 

Juarez, P., Chase, J. and Blomquist, G. J. (1992). A microsomal fatty acid synthetase from the integument of Blattella germanica synthesizes methyl-branched fatty acids, precursors to hydrocarbon and contact sex pheromone. Archives of Biochemistry and Biophysics 293 333-341. 

The synthesis of fatty acids for incorporation into milk fat within the mammary gland is similar to that seen in other tissues. There are two basic reactions the conversion of acetyl-coenzyme A (CoA) to malonyl-CoA, followed by incorporation of the latter into a growing acyl chain via the action of the fatty acid-synthetase complex. However, the product of these reactions in lactating mammary tissue from many species is short and medium chain fatty acids. In most other tissues the product is palmitate. For more complete details see Moore and Christie, (1978), Bauman and Davis (1974), and Patton and Jensen (1976). 

The fatty acid-synthetase complex is located in the cytosol of the... 

Knudsen and Grunnet (1982) have proposed an interesting system for the control of medium-chain fatty acid synthesis by ruminant mammary tissue. Their proposal is based on their observations that ruminant mammary tissue fatty acid-synthetase exhibits both medium-chain thioesterase (Grunnet and Knudsen 1978) and transacylase (Knudsen and Grunnet 1980) activity and that medium-chain fatty acids synthesized de novo can be incorporated into TG without an intermediate activation step (Grunnet and Knudsen 1981). They proposed that the synthesis of the medium-chain fatty acids is controlled by their incorporation into TG (Grunnet and Knudsen 1981). Further work will be needed to substantiate transacylation as a chain-termination mechanism in fatty acid synthesis by ruminant mammary tissue. 

Grunnet, I. and Knudsen, J. 1978. Medium chain acyl-thioester hydrolase activity in goat and rabbit mammary fatty acid synthetase complexes. Biochem. Biophys. Res. Commun. 80, 745-749. 

Knudsen, J. and Grunnet I. 1982. Transacylation as a chain-termination mechanism in fatty acid synthesis by mammalian fatty acid synthetase. Biochem J. 202, 139-143. 

Knudsen, J., Grunnet, I. and Dils, R. 1981. Medium-chain fatty acyl-s-4 -phos-phopantetheine fatty acid synthetase thioester hydrolase from lactating rabbit and goat mammary glands. In Methods in Enzymology, Vol. 710. J.J. Lowenstein (Editor). Academic Press, New York, pp. 200-229. 

Lin, C. Y. and Smith, S. 1978. Properties of the thioesterase component obtained by limited trypsinization of fatty acid synthetase multienzyme complex. J. Biol. Chem. 253, 1954-1962. 

Smith, S. 1976. Structural and functional relationships of fatty acid synthetases from various tissues and species. In Immunochemistry of Enzymes and Their Antibodies. M.G.J. Salton, (Editor). John Wiley Sons, New York, pp. 125-146. 

Smith, S. and Abraham, S. 1971. Fatty acid synthetase from lactating rat mammary gland. Studies on the termination sequence. J. Biol. Chem. 246, 2537-2542. 

Fatty acid synthetase Fatty acyl glucamides Fatty alcohols... 

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