Incorporation of radioactivity from [Me- 14 C] methionine and [2- 14 C]glycine into the lipids of Rhodopseudomonas spheroides

1968 ◽  
Vol 170 (1020) ◽  
pp. 299-310 ◽  
Keyword(s):  
Fatty Acids ◽  
Phospholipid Fraction ◽  
Methyl Group ◽  
Methyl Donor ◽  
Phosphatidylcholine Biosynthesis ◽  
Rhodopseudomonas Spheroides

Radioactivity from L-[Me- 14 C]methionine, in addition to being incorporated into pigments, as found by other workers, was incorporated into phosphatidylcholine, into phosphatidyl N -methylethanolamine and into phosphatidyl N, N -dimethylethanolamine. The latter two compounds were present in trace amounts only. Of the radioactivity in the phospholipid fraction, 90% was in the bases with only minor amounts in the fatty acids. Incorporation was also found into ornithine lipid. The presence of the pathway of phosphatidylcholine biosynthesis which proceeds by the successive methylation of phosphatidylethanolamine was shown by demonstrating a precursor-product relationship between the N -methylated phospholipids and phos­phatidylcholine. Evidence for the presence of the enzymes concerned in the biosynthesis of phosphatidyl­choline by the pathway mentioned and also for the incorporation of the methyl group into ornithine lipid has been obtained in cell-free systems from Rhodopseudomonas spheroides . The methyl donor was S-adenosylmethionine. Radioactivity from [2- 14 C]glycine was incorporated into ethanolamine, into choline and into fatty acids. Ethionine markedly reduced the incorporation into choline without affecting the labelling of ethanolamine. Thus it seems likely that the methyl carbons of choline were radioactive and that ethionine acted by inhibiting transmethylation from S-adenosylmethionine. It is concluded that the α -carbon of glycine gives rise to ‘one carbon’ fragments and also to acetate and the pathways by which these reactions occur are discussed.

The methylating system for 3-sn-phosphatidylcholine biosynthesis in Fusarium oxysporum

1980 ◽  
Vol 26 (7) ◽  
pp. 774-777 ◽  
Author(s):  
Alan C. Wilson ◽  
Leslie R. Barran
Keyword(s):  
Fusarium Oxysporum ◽  
Incubation Temperature ◽  
Specific Activity ◽  
Phospholipid Fraction ◽  
Ph Optimum ◽  
Methyl Group ◽  
Cell Extracts ◽  
Phosphatidylcholine Biosynthesis

Cell extracts of hyphae of Fusarium oxysporum f. sp. lycopersici rapidly transferred the methyl group of S-[methyl-3 H]adenosyl-L-methionine (Ado-Met) to endogenous phosphatidylethanolamine (PE). About 80% of the radioactivity incorporated into the phospholipid fraction was found in phosphatidylcholine (PC) while the rest of the radioactivity was present in the intermediates monomethylphosphatidylethanolamine (MePE) and dimethylphosphatidylethanolamine (DiMePE). The phospholipid methylating system had a pH optimum of 8.5, a Km of 30 μm for Ado-Met, and a Vmax of 10 nmol/h per milligram protein. The specific activity of the methylating system was highest in early log phase and lowest in the late log phase of growth.The activity of the cell-free methylating system was reduced by incubation at temperatures above 25 °C, and at 37 °C about 50% of the initial methylating activity remained after incubation for 15 min. In contrast, the activity of the in vivo methylation system almost doubled when the incubation temperature was raised from 25 to 37 °C.

Quantitative Changes of the Lipid and Fatty Acid Composition of Leaves of Aleurites montana as a Consequence of Growth under 700 ppm CO2 in the Atmosphere

1996 ◽  
Vol 51 (11-12) ◽  
pp. 833-840 ◽  
Author(s):  
P He ◽  
A Radunz ◽  
K. P Bader ◽  
G. H Schmid
Keyword(s):  
Fatty Acids ◽  
Thylakoid Membrane ◽  
Saturated Fatty Acids ◽  
Phospholipid Fraction ◽  
Phospholipid Content ◽  
The Core ◽  
Glycolipid Fraction ◽  
Carbonic Acids ◽  
And Control ◽  
Β Carotene

Abstract Leaf lipids of Aleurites plants that were cultivated for 5 months in air containing 700 ppm CO2, were compared to those of control plants cultivated at 350 ppm CO2. The content of ether soluble lipids referred to dry matter is the same in CO2-and control plants. The comparison of lipids analyzed as the pigments chlorophyll and carotenoids, phospholipids and glycolipids shows that the ratio of phospholipids and glycolipids is slightly shifted in favor of phospholipids in CO2-plants. Thus, within the group of phospholipids, phosphatidylglycerol and phosphatidylinositol occur in higher concentrations in CO2-plants. Although the differences in the lipid content appear moderate in CO2-and control plants, it is the saturation degree of fatty acids that differs substantially. The fatty acids of CO2-plants contain according to the higher phospholipid content approx. 5% more saturated fatty acids. Stearic acid is three-fold increased. Whereas in the phospholipid fraction saturated fatty acids comprise one half of all fatty acids, the unsaturated fatty acids make up for 80 to 90% in the glycolipid fraction. In CO2-plants not only in the phospholipid fraction but also in the glycolipid fraction saturated fatty acids occur in a higher portion. This means that not only in the cell membrane of CO2-plants but also in the thylakoid membrane the fluidity is decreased. Also in the wax-fraction long-chained carbonic acids with 20 -26 carbon atoms occur. As the portion of these carbonic acids is twice as high in CO2-plants, it is concluded that a stronger formation of the wax layers exists in CO2-plants. By means of Western blotting and by the use of lipid and carotenoid antisera the binding of lipids onto proteins of photosystem II and photosystem I was analyzed. It is seen that besides the major amount of lipids which build up the thylakoid membrane, some lipids are also bound to membrane peptides. Whereas monogalactolipid is bound to the LHCP-complex peptides, to the OEC1 -peptide and the 43 and 47 kDa chlorophyll binding peptides, the anionic lipids sulfoquinovosyldiglyceride and phosphatidylglycerol and digalactolipid are bound to the core peptides of PS II and PS I. β-carotene and the xanthophylls were found to be bound to the core peptides and β-carotene and violaxanthin were also bound to the light-harvesting pigment complex.

Structural Homogeneity in Unsaturated Fatty Acids of Marine Lipids. A Review

1964 ◽  
Vol 21 (2) ◽  
pp. 247-254 ◽  
Author(s):  
R. G. Ackman
Keyword(s):  
Fatty Acids ◽  
Double Bond ◽  
Polyunsaturated Fatty Acids ◽  
Chain Length ◽  
Unsaturated Fatty Acids ◽  
Analytical Data ◽  
Double Bonds ◽  
Marine Origin ◽  
Methyl Group ◽  
Marine Lipids

Consideration of recent analytical data supports the conclusion that the longer-chain polyunsaturated fatty acids of marine origin are all structurally homogeneous in that the double bonds are cis, the double bonds methylene interrupted, and that, with the exception of the C16 chain length, the ultimate double bond will normally be three, six or nine carbon atoms removed from the terminal methyl group.

A Possible Mechanism for a Light-Driven Regulation of the Fatty Acid Composition in Galactolipids of Chloroplasts

1979 ◽  
Vol 34 (9-10) ◽  
pp. 815-819
Author(s):  
A. Sauer ◽  
K .-P. Heise
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Unsaturated Fatty Acids ◽  
Specific Activity ◽  
Physiological State ◽  
Phospholipid Fraction ◽  
Chromatographic Behavior ◽  
Acyl Acceptor ◽  
Lipid Mixture ◽  
Spinach Leaves

Abstract The occurrence of acylgalactosylglycerol (AGG) in spinach chloroplasts is proposed. In lipid se­parations of whole spinach leaves this fraction is hidden by variable amounts of extraplastidary steryl glucoside (SG) which depended on the physiological state of the leaf material. Beside the phospholipid fraction, this lipid mixture with unique chromatographic behavior, recently termed GL, exhibited the highest specific activity in the lipid extract of infiltrated leaf sections of spinach after short periods of illumination (2 min) under 14C-fixing conditions. The main source of label was found in the fatty acid residues of the lipids described. The decrease of specific activity in GL after a cold chase was accompanied by an increasing 14C-incorporation into the fatty acid moieties of the MGDG-as well as the phospholipid fraction. This effect was significantly reduced if the 14C-pulse was followed by a dark period. This incorporation behavior suggests, that AGG functions as an intermediary acyl acceptor in the light driven fatty acid transfer between the lipids decribed. SG-synthesis, on the contrary, is independent of additional illumination and seems to be localized outside the chloroplast. The last notion was derived from experiments involving the in­ corporation of [UDP-14C] glucose into SG by spinach leaf homogenates. With regard to the increasing level of trienoic fatty acids in AGG and MGDG during the regeneration of dark pretreated spinach leaves in the light, the data are interpreted in terms of a light regulated acylation of AGG with specific unsaturated fatty acids.

Intermediary metabolism of Acinetobacter grown on dialkyl ethers

1989 ◽  
Vol 35 (11) ◽  
pp. 1031-1036 ◽  
Author(s):  
Malcolm C. Modrzakowski ◽  
William R. Finnerty
Keyword(s):  
Fatty Acids ◽  
Dicarboxylic Acid ◽  
Chain Length ◽  
Dicarboxylic Acids ◽  
Acid Oxidation ◽  
Methyl Group ◽  
Ether Oxygen ◽  
Dialkyl Ethers ◽  
Long Chain ◽  
Methyl Group Oxidation

The microbial dissimilation of long-chain dialkyl ethers by Acinetobacter sp. H01-N involved a terminal methyl group oxidation of the dialkyl ether substrates, resulting in the formation of ether oxygen containing fatty acids of corresponding chain length. An internal carbon–carbon scission of the dialkyl ethers resulted in the formation of end-product ether fatty acids and corresponding dicarboxylic acids. Cellular carbon and energy were derived from the subsequent metabolism of the dicarboxylic acids. Dicarboxylic acid oxidation, activation, and identification of cellular dicarboxylic acids indicated dibasic acids as intermediates in the metabolism of dialkyl ethers.Key words: dialkyl ethers, dicarboxylic acids, fatty acids, Acinetobacter.

scholarly journals The effect of dihomo-γ-linolenic acid (20: 3, n-6) on the composition of phospholipid fatty acids in the liver of rats deficient in essential fatty acids

1978 ◽  
Vol 40 (1) ◽  
pp. 155-157 ◽  
Author(s):  
A. G. Hassam ◽  
M. A. Crawford
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Linoleic Acid ◽  
Linolenic Acid ◽  
Essential Fatty Acid ◽  
Essential Fatty Acids ◽  
Phospholipid Fatty Acids ◽  
Phospholipid Fraction ◽  
Liver Phospholipid ◽  
Dietary Energy

1. Rats were fed on either a diet deficient in essential fatty acid (EFA) or one supplemented with dihomo-γ-linolenic acid (20:3,n-6) at levels that represented 0.25, 0.5, 1.0 and 2.0% of the dietary energy.2. Supplementation of the diet of EFA-deficient animals with 20:3,n-6 reversed most of the fatty acid changes induced in the liver phospholipid fraction.3. The EFA potency of 20:3,n-6 was found to be similar to that of γ-linolenic acid (18:3,n-6) which has been shown to be higher than that of linoleic acid (18:2,n-6).

Phosphatidylcholine metabolism: masochistic enzymology, metabolic regulation, and lipoprotein assembly

1990 ◽  
Vol 68 (10) ◽  
pp. 1151-1165 ◽  
Author(s):  
Dennis E. Vance
Keyword(s):  
Fatty Acids ◽  
Endoplasmic Reticulum ◽  
Metabolic Regulation ◽  
Alternative Pathway ◽  
Plasma Lipoproteins ◽  
High Density Lipoproteins ◽  
Very Low Density Lipoproteins ◽  
Major Pathway ◽  
Phosphatidylcholine Biosynthesis ◽  
Membrane Bound

Phosphatidylcholine is apparently essential for mammalian life, since there are no known inherited diseases in the biosynthesis of this lipid. One of its critical roles appears to be in the structure of the eucaryotic membranes. Why phosphatidylcholine is required and why other phospholipids will not substitute are unknown. The major pathway for the biosynthesis of phosphatidylcholine occurs via the CDP-choline pathway. Choline kinase, the initial enzyme in the sequence, has been purified to homogeneity from kidney and liver and also catalyzes the phosphorylation of ethanolamine. Most evidence suggests that the next enzyme in the pathway, CTP:phosphocholine cytidylyltransferase, catalyzes the rate-limiting and regulated step in phosphatidylcholine biosynthesis. This enzyme has also been completely purified from liver. Cytidylyltransferase appears to exist in the cytosol as an inactive reservoir of enzyme and as a membrane-bound form (largely associated with the endoplasmic reticulum), which is activated by the phospholipid environment. There is evidence that the activity of this enzyme and the rate of phosphatidylcholine biosynthesis are regulated by the reversible translocation of the cytidylyltransferase between membranes and cytosol. Three major mechanisms appear to govern the distribution and cellular activity of this enzyme. (i) The enzyme is phosphorylated by cAMP-dependent protein kinase, which results in release of the enzyme into the cytosol. Reactivation of cytidylyltransferase by binding to membranes can occur by the action of protein phosphatase 1 or 2A. (ii) Fatty acids added to cells in culture or in vitro causes the enzyme to bind to membranes where it is activated. Removal of the fatty acids dissociates the enzyme from the membrane, (iii) Perhaps most importandy, the concentration of phosphatidylcholine in the endoplasmic reticulum feedback regulates the distribution of cytidylyltransferase. A decrease in the level of phosphatidylcholine causes the enzyme to be activated by binding to the membrane, whereas an increase in phosphatidylcholine mediates the release of enzyme into the cytosol. The third enzyme in the CDP-choline pathway, CDP-choline: 1,2-diacylglycerol cholinephosphotransferase, has been cloned from yeast but never purified from any source. In liver an alternative pathway for phosphatidylcholine biosynthesis is the methylation of phosphatidylethanolamine by phosphatidylethanolamine N-methyltransferase. This enzyme is membrane bound and has been purified to homogeneity. It catalyzes all three methylation reactions involved in the conversion of phosphatidylethanolamine to phosphatidylcholine. The activity of this enzyme is 100- to 1000-fold lower in other cells and tissues derived from animals. In yeast there are two phospholipid methyltransferases involved in the methylation of phosphatidylethanolamine. The genes encoding both of these enzymes have been cloned and the primary structure of the enzymes have been deduced. Phosphatidylcholine is also catabolized in liver. Only one enzyme involved in this process has been purified to homogeneity, that is, phospholipase A2 from mitochondria. The mechanisms involved in the regulation of phosphatidylcholine catabolism are largely unknown. Phosphatidylcholine is a major component of plasma lipoproteins and the active synthesis of phosphatidylcholine is required for the secretion of very low density lipoproteins from liver. In contrast, the secretion of high density lipoproteins, albumin, and all other secreted proteins do not require the active biosynthesis of phosphatidylcholine. Other phospholipids will not substitute for the phosphatidylcholine requirement. It is also apparent that newly made phosphatidylcholine, rather than preexisting phosphatidylcholine, is preferentially utilized for lipoprotein secretion.Key words: phosphatidylcholine, glycerophosphocholine, cytidylyltransferase, methyltransferase, cholinephosphotransferase.

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