Fatty acids chain elongation

Figure 21-S. Microsomal elongase system for fatty acid chain elongation. NADH is also used by the reductases, but NADPH is preferred.

Cinti, D. L., Cook, L., Nagi, M. N. and Suneja, K. J. The fatty acid chain elongation system of mammalian endoplasmic reticulum. Prog. Lipid Res. 31 1-51,1992. 

Figure 3.6. Polyketlde chains use an iterative process akin to the fatty acid chain elongation process. However, an extra layer of chemical diversity can be generated by feeding different starter units into the system consequently, the polyketlde biosynthetic system has been compared to a Lego system where a few modules can be joined together in many different ways.

All of the following are true about long-chain fatty acid chain elongation except... 

Figure 1). These 8-keto and -hydroxy acids also could be viewed as Intermediates In a pathway toward the fully saturated extended-chain metabolite. Thus, while 6-hydroxy, -keto, and 0,0-unsaturated Intermediates are usually not abundant species in natural fatty acid chain elongation (I.e. the fully saturated product predominates), these intermediary metabolites may be quantitatively Important for xenobiotic acids.

ER fatty acid chain elongation, which uses two-carbon units provided by mal-onyl-CoA, is a cycle of condensation, reduction, dehydration, and reduction reactions similar to those observed in cytoplasmic fatty acid synthesis. In contrast to the cytoplasmic process, the intermediates in the ER elongation process are CoA esters. These reactions can lengthen both saturated and unsaturated fatty acids. Reducing equivalents are provided by NADPH. 

Brenner, R.R. (1989) Factors Influencing Fatty Acid Chain Elongation and Desaturation, in The Role of Fats in Human Nutrition (Vergroesen, A.J., and Crawford, M., eds.) 2nd edn., pp. 45-79, Academic Press, London. 

The Mechanisms of Fatty Acid Chain Elongation and Desaturation in Animals... 

In 1969 he received the Heinrich Wieland award for his work on fatty acid chain elongation in mitochondria, and in 1970 he was elected to membership in the Academy of Science in Gottingen. 

His studies and interest in fatty acid chain elongation started at Prof. Lynen s laboratory during the fifties. At that time he showed that fatty acids can be synthesized from acetyl-CoA in the presence of NADH and NADPH hy reversal of fatty acid oxidation in an Zn VaXXO system containing thiolase, 3 hydroxyacl-CoA dehydrogenase, crotonase, and a newly found "reducing enzyme" (enoyl-CoA reductase) from pig liver and yeast. 

Liver microsomes were the site of fatty acid chain-elongation activity (Guchhait et al., 1966 Nugteren, 1965) and desaturation (Marsh and James, 1962). Aeberhard and Menkes (1968) reported that brain microsomes were additionally capable of synthesis de novo under certain conditions. The microsomes are probably not responsible for the net synthesis of a substantial quantity of fatty acids, but their functional importance appears to be as modifier of the products of synthesis. 

An inadequacy of the fatty acid chain elongation process with a concomitant deficit of cerebrosides was discussed as one of the early biochemical lesions in brain white matter of patients with multiple sclerosis (Gerstil et ah, 1970). 

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