Oleic Acid Biosynthesis Research Articles

Une nouvelle voie de biosynthèse de l'acide oléique dans les végétaux

Oleic acid biosynthesis in Cauliflower slices has been studied from the following radioactive precursors: 14C-acetate, 14C-decanoate, 14C-laurate, 14C-palmitate, 14C-stearate and 14C-hydroxyacids derived from 14C-decanoate. The higher incorporation yield was obtained withe 14C-decanoate or the hydroxyacids derived from it. A new biosynthetic pathway for oleic acid, implying the intervention of a β-γ-hydroxylaurate-dehydrase is discussed. La biosynthèse de l'acide oléique dans des tranches d'inflorescences du Chou-fleur a été étudiée à partir des précurseurs radioactifs suivants: acétate-14C, décanoate-14C, laurate-14C, palmitate-14C, stéarate-14C et hydroxyacides-14C dérivés du décanoate. Le rendement d'incorporation le plus élevé a été obtenu avec le décanoate ou les hydroxyacides dérivés. Un schéma de biosynthèse impliquant l'intervention d'une β-γ-hydroxylaurate déhydrase est discuté.

The effect of methyl sterculate on oleic acid synthesis in the hen

AbstractThe enzymic desaturation of saturated fatty acids to monoenes in animals and plants is inhibited by cyclopropene fatty acids, such as sterculic acid. Labeled acetic and stearic acids were administered to laying hens which had received methyl sterculate in the diet for long periods, and the incorporation of the label in the eggs and liver was studied. The egg was used as a “biological trap” to study the metabolism of the hen in relation to its diet. Maximum incorporation of label was observed in the third or fourth egg laid after administration of the labeled compound. Dietary methyl sterculate reduced the incorporation of stearic acid into egg yolk lipids, but the incorporation of acetate was not affected. The formation of oleic acid was inhibited by methyl sterculate irrespective of whether the prescursor was acetate or stearate acid. In laying hens receiving methyl sterculate for long periods, no evidence could be obtained for the biosynthesis of oleic acid by an alternative pathway which did not involve the desaturation of stearic acid. The validity of comparing the ratio of the specific activities of stearic acid and oleic acid in control birds with the corresponding ratio obtained for birds receiving methyl sterculate is questioned, because the sizes of the metabolic pools of the product and precursors may be quite different for the two groups of birds.

Localization of oleic acid biosynthesis enzymes in the proplastids of developing castor endosperm

The particulate fatty acid synthesizing system from the developing castor bean endosperm was separated using sucrose density gradients. The particulate fatty acid synthesizing enzymes were associated with a particle of peak density 1.21 g∙(cm3)−1. Based on the presence of triosephosphate isomerase and the appearance of the particles in electron micrographs the major constituent of this fraction was identified as proplastids. It appears that in this tissue the proplastid contains the complete enzyme complement for oleic acid synthesis from acetyl or malonyl-CoA.

Fat metabolism in higher plants XLIX fatty acid biosynthesis by subcellular fractions of higher plants

AbstractA method is described for the rapid and comprehensive subcellular fraction‐ation of plant tissue using a combination of differential and discontinuous Ficoll gradient centrifugation. The procedure has been used to study the synthesis of fatty acids from acetate‐1‐14C or malonyl CoA‐1,3‐14C, by fractions of germinating pea and lupin seeds and developing avocado fruit, castor bean and safflower seeds. Particle free supernatants of seeds synthesize fatty acids from14C‐malonyl CoA in the presence of added cofactors. Since acetyl CoA carboxylase activity is absent the utilization of14C‐acetate by these fractions is minimal. Other particulate fractions show different activities depending on seed types. Active fractions include the low speed particulate of pea and lupin, the pea microsomes, the avocado mesocarp chloroplasts, and the fat fractions of castor bean and safflower. Individual fractions produce characteristic patterns of acids; especially noteworthy is oleic acid biosynthesis by soluble enzymes of castor bean and safflower from14C‐malonyl CoA. Some characteristics of the avocado supernatant, pea supernatant, and castor bean fat fraction synthesizing systems are compared. As a result of these studies, generalizations derived from work with mammalian or bacterial systems cannot be applied to higher plants.

Subcellular localization of oleic acid biosynthesis enzymes in the developing castor bean endosperm

The complete enzyme complement for oleic acid synthesis from acetyl-CoA or malonyl-CoA was associated with subcellular particles (density 1.21g/cc) isolated from developing castor seed endosperm. These particles were either the proplastids or a new unique particle.

Alternate route for the biosynthesis of oleic acid in the rat

1. 1. Adult rats were given by stomach tube 10 μC of methyl [1- 14]stearate dissolved in either corn oil or Sterculia foetida seed oil. After 3 h they were injected with 200 μC of [ 3H]acetate and were sacrificed 1 h later. The 3H and 14C specific radioactivities of the stearic acid in the liver lipids of the corn oil controls were nine times as high as in the oleic acid. When S. foetida oil was in the diet, the 14C ratio was about 1500 whereas the 3H ratio was only 14, showing that stearic acid desaturation to oleic acid was inhibited but not acetate conversion to oleic acid. 2. 2. When a similar study was carried out in which methyl [1- 14C]laurate and methyl [11,12- 3H 2]stearate were given, the 3H ratio in the corn oil controls was about 8 and the 14C ratio was about 2, indicating that laurate acted as a precursor for oleic acid biosynthesis. Inclusion of S. foetida seed oil resulted in an increase in the 3H ratio to about 1600 whereas the 14C ratio was increased to only 12, showing that lauric like acetate conversion is not inhibited by cyclopropene fatty acids. Permanganate oxidation studies of the isolated octadecenoic acids indicated that when S. foetida seed oil was given, about 90% of the octadecenoate radioactivity was in oleic, and 90% of the oleic acid activity due to 14C was in the azelaic acid fraction. This suggests the intact utilization of lauric acid for oleic acid synthesis, probably by β,γ-desaturation followed by elongation.

The stereochemistry of desaturations of long-chain fatty acids in Chlorella vulgaris

1. A study was made of the stereospecificity of hydrogen removal in the sequential desaturations performed by intact cells of Chlorella vulgaris in the biosynthesis of oleic acid, linoleic acid and alpha-linolenic acid. 2. By use of erythro- and threo-9,10-(2)H(2)-, -12,13-(2)H(2)- and -15,16-(2)H(2)-labelled precursors, it was demonstrated that the pair of hydrogen atoms removed from each of these positions had the cis relative configuration. 3. That the hydrogen atoms removed in oleic acid and linoleic acid formation were of the d absolute configuration was proved by use of d- and l-9-(3)H-and -12-(3)H-labelled precursors. 4. The presence of a substantial kinetic isotope effect of deuterium at both positions of the putative double bond was indicated, suggesting that the mechanism of desaturation involves simultaneous concerted removal of the pair of hydrogen atoms.

The biosynthesis of long-chain fatty acids by lettuce chloroplast preparations

1. 1. It is demonstrated that the major site of biosynthesis of saturated fatty acids from C 10 to C 18 and of oleic acid in leaves is the chloroplast. 2. 2. The co-factors required in the presence of light are ATP, CoA, Mg 2+, CO 2 and inorganic phosphate. 3. 3. In the dark greatly diminished synthesis occurs despite the presence of a full complement of cofactors. 4. 4. As in photosynthetic phosphorylation the synthesis of fatty acids is inhibited by NH 3 and 3( p-chlorophenyl) 1,1-dimethyl urea but not by dinitrophenol. 5. 5. Under anaerobic conditions the biosynthesis of oleic acid drops markedly but that of the saturated acids is relatively unaffected. 6. 6. Isolated chloroplasts are less effective in utilising the C 8, C 10, C 12 and C 14 saturated fatty acids for the biosynthesis of oleic acid than is the intact leaf. Both malonic and acetic acids are, however, readily utilised.

The biosynthesis of long-chain fatty acids by lettuce chloroplast preparations

1. 1. It is demonstrated that the major site of biosynthesis of saturated fatty acids from C 10 to C 18 and of oleic acid in leaves is the chloroplast. 2. 2. The co-factors required in the presence of light are ATP, CoA, Mg 2+, CO 2 and inorganic phosphate. 3. 3. In the dark greatly diminished synthesis occurs despite the presence of a full complement of cofactors. 4. 4. As in photosynthetic phosphorylation the synthesis of fatty acids is inhibited by NH 3 and 3( p-chlorophenyl) 1,1-dimethyl urea but not by dinitrophenol. 5. 5. Under anaerobic conditions the biosynthesis of oleic acid drops markedly but that of the saturated acids is relatively unaffected. 6. 6. Isolated chloroplasts are less effective in utilising the C 8, C 10, C 12 and C 14 saturated fatty acids for the biosynthesis of oleic acid than is the intact leaf. Both malonic and acetic acids are, however, readily utilised.

The conversion of [formula omitted]-2-octenoic acid to linoleic acid

Scheuerbrandt et , al . (1961) have reported the anaerobic biosynthesis of oleic acid from octanoate by Clostridium , butyricum . At the same time, it was reported from this laboratory that 1-C 14- cis -2-octenoic acid may be converted into linoleic acid by the laying hen (Reiser et , al . 1961, 1962). The synthetic steps suggested by Scheuerbrandt et , al . (1961) may explain both syntheses, as diagrammed below in the discussion. In the present study, unlabeled cis -2-octenoic acid was fed and the hen injected with 1-C 14 acetate. More direct and rigorous techniques than in the earlier work were used for the location of the labeled carbon atoms in the resultant linoleic acid.