Animal cell membranes consist of fatty materials of which fatty acids are vital membrane components. Some of these fats cannot be made in the body they include fatty acids called LA and
It the meantime here's some comments from two recent scientific papers I have read to partly document my remarks.Paper 1. The biochemical details.
Molecules of Interest: Eicosapentaenoic acid: biosynthetic routes and the potential for synthesis in transgenic plants.
Olga V. Sayanova, Johnathan A. Napier* Rothamsted Research, Harpenden,
This review is dedicated to the memory of Dr. David Horrobin (1939–2003).
Phytochemistry 65 (2004) 147–158
Long chain polyunsaturated fatty acids are now known to play important roles in human health. In particular, eicosapentaenoic acid (20:5delta 5,8,11,14,17; n-3: EPA) is implicated as a protective agent in a range of pathologies such as cardiovascular disease and Metabolic Syndrome (Syndrome X). Eicosapentaenoic acid is currently sourced from fish oils, the presence of this fatty acid being due to the dietary piscine consumption of EPA-synthesising micro-algae. The biosynthetic pathway of EPA has been elucidated, and contains several alternative metabolic routes. Progress in using ‘‘reverse engineering’’ to transgenically mobilize the trait(s) for EPA are considered. In particular, the prospect of producing this important polyunsaturated fatty acid in transgenic oilseeds is highlighted, as is the urgent need for a sustainable replacement for diminishing fish stocks.Animal cell membranes primarily consist of a bilayer of phospholipids and cholesterol with imbedded proteins that act as receptors, transporters and enzymes.The phospholipid fatty acid composition determines thephysical and functional properties of cell membranesand has important implications for cell integrity and growth, inflammation and immunity. This is defined by the fatty acids esterified to the glycerol backbones, with chain length and unsaturation acting as key determinants.The role(s) of 20-carbon (C20) polyunsaturated fatty acids (PUFAs) with methylene interrupted double bonds have been the recent focus of intensive research on fatty acid functionality. For the purpose of this review, PUFAs are defined as containing three or more double bonds on a fatty acid chain of 18 or more carbons. PUFAs can be further classified into two families (n-6 or n-3), depending on the position of the last double bond proximal to the methyl end of the fatty acid. These n-6 and n-3 fatty acids (also sometimes called omega-3 and omega-6 fatty acids) are derived from the essential fatty acids (EFA) linoleic acid (LA, 18:2_9,12) and a-linolenic acid (ALA, 18:3delta9,12,15), respectively. Both of these precursor fatty acids are synthesized by plants, but not mammals; therefore they are essential dietary components of all mammals and hence their designation as EFAs. Through a series of acyl desaturation and elongation reactions, LA is metabolized to arachidonic acid (AA, 20:4delta 5,8,11,14; n-6) and ALA is metabolized to eicosapentanoic acid (EPA, 20:5delta 5,8,11,14,17; n-3) and docosahexaenoic acid (DHA, 22:6delta 4,7,10,13,16,19).
Thus the n-6 (LA) and n-3 (
Department of Medicine,