The Biosynthesis of Fatty Acids in the Cellular Slime Mold, Dictyostelium discoideum
Year: 1963
Type: article
Abstract: Although considerable progress has been made in recent years in understanding the biosynthesis of saturated fatty acids, the mechanisms of de&u&ion of fatty acids are still largely obscure.Recent studies have, however, demonstrated the existence of three general pathways: the direct desaturation of long chain saturated fatty acids by a process requiring molecular oxygen and reduced nicotinamide adenine dinucleotide phosphate (l), the introduction of double bonds during the process of synthesis of the fatty acid chain (2), and the elongation of long chain unsaturated acids at the carboxyl end by addition of 2 carbon units, followed by further desaturation (3).The cellular slime mold Dictyostelium discoideum has been found to contain a high percentage of unsaturated fatty acids (4).Several of these are unique dienoic acids that do not contain the methylene-interrupted double bonds present in most natural polyenoic fatty acids.For reasons that will be developed later, the major fatty acids of this organism may be divided into three metabolic groups: (a) palmitic acid, 16:0,1 palmitoleic acid, 16:1(g), and a diunsaturated acid, 16:2(5,9); (b) cis-vaccenic acid, 18 : l(ll), and an 18 carbon diunsaturated acid, 18:2(5,11); and (c) stearic acid, 18:0, oleic acid, 18:1(g), and a diunsaturated acid, 18:2(5,9).The occurrence of this mixture of distinctive monoenoic and dienoic fatty acids has afforded a convenient system for studying the biosynthesis of unsaturated fatty acids.In the present paper are reported experiments on the synthesis in growing cells of unsaturated fatty acids from radioactive short and long chain saturated fatty acids.The distribution of radioactivity among the fatty acids of the ameba was determined, as was also the distribution of radioactivity within individual unsaturated fatty acids.The results indicate that palmitate serves as the common precursor for 16:1(g), 16:2(5,9), 18:1(11), and18:2 (5,11), andthat 18:1(g) and 18:2(5,9) are derived from stearate, which in turn may be derived from palmitate.
Source: Journal of Biological Chemistry
Authors: Frank Davidoff, Edward D. Korn
Language: English
Subfield: Biochemistry
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W190803907