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1.
Martin aus dem Kahmen Hans J. Schfer 《European Journal of Lipid Science and Technology》1998,100(6):227-235
Diels-Alder reactions with methyl conjuenate ( 2 ) at room temperature, with methyl E-12-oxo-10-octadecenoate ( 11 ) as dienophile and radical cation catalyzed cycloadditions of 2 are described. 2 is prepared from methyl linoleate by base catalyzed isomerization with sodium dimethylsulfoxide in 90% yield. It undergoes readily Diels-Alder reactions at room temperature in the presence of 1–1.8 equivalents of a Lewis acid and catalytic amounts of iodine to form cycloadducts in 55–90% yield. At 140°C 2 reacts with dimethyl maleate and dimethyl acetylenedicarboxylate to cycloadducts in 86% and 73% yield, respectively. Methyl E-12-oxo-10-octadecenoate ( 11 ) can be combined in a Diels-Alder reaction with the dienes 2-(trimethylsilyloxy)-1,3-butadiene and 2,3-dimethylbutadiene in 69% and 86% yield, respectively. By way of radical cation catalysis 2 undergoes [4+2]-cycloadditions with dienes in high yield. 相似文献
2.
Neurospora crassa incorporated exogenous deuterated palmitate (16∶0) and 14C-labeled oleate (18∶1Δ9) into cell lipids. Of the exogenous 18∶1Δ9 incorporated, 59% was desaturated to 18∶2Δ9,12 and 18∶3Δ9,12,15. Of the exogenous 16∶0 incorporated, 20% was elongated to 18∶0, while 37% was elongated and desaturated into 18∶1Δ9, 18∶2Δ9,12, and 18∶3Δ9,12,15. The mass of unsaturated fatty acids in phospholipid and triacylglycerol is 12 times greater than the mass of 18∶0. Deuterium
label incorporation in unsaturated fatty acids is only twofold greater than in 18∶0, indicating a sixfold preferential use
of 16∶0 for saturated fatty acid synthesis. These results indicate that the release of 16∶0 from fatty acid synthase is a
key control point that influences fatty acid composition in Neurospora. 相似文献
3.
Quondam M; Barbato C; Pickford A; Helmer-Citterich M; Macino G 《Protein engineering, design & selection : PEDS》1997,10(9):1047-1055
A model of the tertiary structure of the Neurospora crassa carotenogenic
prenyltransferase, geranylgeranyl pyrophosphate synthase (GGPPS), is
presented, based on structural homology with other prenyltransferases and
on the crystal structure of recombinant avian farnesyl pyrophosphate
synthase (FPPS). The conserved aspartate-rich motifs DDxx(xx)D and
associated basic residues, considered to be the active sites for binding
and catalysis in all prenyltransferases, are highly conserved in the N.
crassa GGPPS protein, while other regions display a lower degree of
sequence homology; thus the GGPPS model structure is predicted to be highly
reliable in the active site region. A number of carotene-deficient mutants
have been generated utilizing the repeat-induced point mutation (RIP)
mechanism: mutant al-3RIP1 carries a Ser-to-Asn mutation in position 336
which falls within the predicted active site of the enzyme. Analysis of the
model structure of this mutant indicates that Ser336 may be involved in
substrate uptake. Two other mutants, al-3RIP3 and al-3RIP6, carry mutations
in positions in the GGPPS protein, homologous to regions of the avian FPPS
enzyme proposed to be involved in enzyme dimerization and substrate uptake,
respectively, suggesting an explanation for the reduced carotene content of
these mutants.
相似文献
4.
The use of copper and cadmium oxides or soaps as catalysts for the hydrogenation of unsaturated fatty acids to unsaturated
fatty alcohols has been investigated. It is shown that copper soaps homogeneously activate hydrogen. When copper and cadmium
oxides are used as catalysts, they react with the acid under formation of a homogeneous soap solution. A continuous reaction
system for the preparation of unsaturated fatty alcohols by hydrogenation under the influence of copper and cadmium soaps
is described. 相似文献
5.
Elaidination of unsaturated fatty acids usingp-toluenesulfinic acid yielded 77–80% totaltrans unsaturation in the products. Results from reactions with monoene, diene, and triene isomers indicated that only geometric
isomerization takes place. Each double bond isomerized randomly and independently in the polyunsaturated fatty acids. Reactions
proceeded quickly, and the method proved convenient and reliable. 相似文献
6.
Fatty acid distillates (FADs) produced during physical refining of vegetable oil contains large amount of free fatty acid. A mutant of Candida tropicalis (M20) obtained after several stages of UV mutation are utilized to produce dicarboxylic acids (DCAs) from the fatty acid distillates of rice bran, soybean, coconut, palm kernel and palm oil. Initially, fermentation study was carried out in shake flasks for 144 h. Products were isolated and identified by GLC analysis. Finally, fermentation was carried out in a 2 L jar fermenter, which yielded 62 g/L and 48 g/L of total dibasic acids from rice bran oil fatty acid distillate and coconut oil fatty acid distillate respectively. FADs can be effectively utilized to produce DCAs of various chain lengths by biooxidation process. 相似文献
7.
Phosphatidylglycerolphosphate (PGP) synthase and PGP phosphatase catalyze the sequential synthesis of phosphatidylglycerol
from cytidine-5′-diphosphate 1,2-diacyl-sn-glycerol (CDP-DG) and glycerol-3-phosphate. PGP synthase and PGP phosphatase activities were characterized in rat heart mitochondrial
fractions, and the effect of fatty acids on the activity of these enzymes was determined. PGP synthase was observed to be
a heat labile enzyme that exhibited apparent Km values for CDP-PG and glycerol-3-phosphate of 46 and 20 μM, respectively. The addition of exogenous oleic acid to the assay
mixture did not affect PGP synthase activity. PGP phosphatase was observed to be a heat labile enzyme, and addition of oleic
acid to the assay mixture caused a concentration-dependent stimulation of PGP phosphatase activity. Maximum stimulation (1.9-fold)
of enzyme activity was observed in the presence of 0.5 mM oleic acid, but the stimulation was slightly attenuated by the presence
of albumin in the assay. The presence of oleic acid in the assay mixture caused the inactivation of PGP phosphatase activity
to be retarded at 55°C. Stimulation of PGP phosphatase activity was also observed with arachidonic acid, whereas taurocholic,
stearic and palmitic acids did not significantly affect PGP phosphatase activity. The activity of mitochondrial phosphatidic
acid phosphohydrolase was not affected by inclusion of oleic acid in the incubation mixture. We postulate that unsaturated
fatty acids stimulate PGP phosphatase activity in rat heart. 相似文献
8.
Summary Methyl oleate, oleic acid, and ethyl linoleate were chlorinated with elemental chlorine at temperatures near −20°C. Approximately
quantitative yields of the addition products were obtained, with little or no concurrent substitution. The products prepared
in this manner had not previously been reported in the pure state. Two new compounds, ethyl tetrachlorostearate and tetrachlorostearic
acid, were prepared.
Methyl dichlorostearate was found to distil with no apparent decomposition at 190–200°C. under pressures below 1 mm. Removal
of the chlorine atoms required more drastic conditions that removal of bromine atoms from the same positions and was accompanied
by complicating side reactions.
Journal Paper No. 755 of the Purdue University Agricultural Experiment Station, Lafayette, Ind. 相似文献
9.
M. Hashmi M. Khan M. S. Ahmad F. Ahmad S. M. Osman 《Journal of the American Oil Chemists' Society》1983,60(8):1538-1543
The reaction of 10-undecenoic acid with lead tetraacetate (LTA) in the presence of acetic acid and anhydrous potassium acetate
gave a eutectic mixture of 10(11)-acetoxy-11(10)-methylundecanoic acid (25%), 10,11-diacetoxyundecanoic acid (15%) and 5-(ω-carboxyoctyl)
γ-butyrolactone (45%). Similar reaction withcis-9-octadecenoic acid yielded a eutectic mixture of 9(10)-acetoxy-10(9)-methyloctadecanoic acid (20%) and 4(5)-(ω-carboxyheptyl)-5-(4)-octyl
γ-butyrolactone (40%). In the reaction withtrans-2-enoic acids (C16 and C18) products obtained were: 1,2-diacetoxypenta- and heptadecane (27%), 3-acetoxyhexa- and octadecanoic acid (31%) and 2-(2-penta-
and heptadecyl) succinic anhydride (23%), respectively. The structures of individual compounds were characterized by spectral
methods. 相似文献
10.
The conversion of oleic acid to 10-hydroxystearic acid with resting cells ofNocardia cholesterolicum (NRRL 5767) has been previously reported. These same microorganisms also convert linoleic and linolenic acids to 10-hydroxy-12c-octadecenoic and 10-hydroxy-12c,15c-octadecadienoic acids, respectively. The reaction occurs best at 35°C and a pH of 6.5. Under optimum conditions, 75–80% of
the unsaturated fatty acid substrate is converted to the corresponding hydroxy acid. The hydroxy products were characterized
by gas chromatography, gas chromatographymass spectrometry, nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy.
Other microorganisms that successfully converted these substrates include another strain ofNocardia cholesterolicum (NRRL 5768) andNocardia sp. (NRRL 5636).
Presented at the 82nd Annual meeting of the American Oil Chemists’ Society, Chicago, IL, May 12–15, 1991. 相似文献
11.
A study was made of the influence of semisynthetic diets of low and high unsaturation on the fatty acid composition and desaturation-chain
elongation enzymatic activity of the liver microsomal fractions of male Sprague-Dawley rats of different ages. Groups of rats
were fed 5 or 20% coconut oil (CO), or a 5 or 20% mixture of corn and menhaden oils (3∶7) (CME) from weaning to 100 wk of
age. Growth rate and food consumption were measured during this period in which animals were sacrificed at 36, 57, 77 and
100 wk of age. Both the level and composition of the dietary fat supplements produced marked effects on the fatty acid composition
of the liver microsomal lipids. In general, the fatty acid composition of the microsomal fractions reflected that of the dietary
fat and was more unsaturated with the higher level of fat fed. The rate of conversion of linoleic to arachidonic acid in assays
performed in vitro with liver microsomal preparations from animals of the different groups also showed marked differences.
The 6-desaturase-chain elongation activity was higher in the 5% than 20% group and corresponded to the essential fatty acid
(EFA) status of the animals in these groups as represented by the triene-tetraene ratio of the microsomal lipid. The relationship
of the 6-desaturase activity to fatty acid composition of the microsomal lipid indicated that if varied directly with the
level of 20∶3ω9, 18∶1 and 16∶1 and was inhibited by arachidonic acid. The activity of the 6-desaturase enzyme system was lowest
in the liver microsomal fraction obtained from the animals fed the CME diets and appeared to be suppressed by the high levels
of 20∶5 and 22∶6 that accumulated in the microsomal lipid. Accordingly, the levels of arachidonic acid were lower in the microsomal
lipid of these groups than those of the corresponding CO groups in spite of a greater abundance of linoleic acid in the diet.
The data suggest that the activity of the 6-desaturase-chain elongation system is regulated by the fatty acid composition
of the microsomal lipid as influenced by the composition of the dietary fat. 相似文献
12.
Bottino NR 《Lipids》1967,2(2):155-160
Rats fed a fat-free diet from weaning were contined on that diet alone or supplemented with methyl linoleate, methyl linoleate
plus a mixture of antibiotics, or methyl arachidonate.
Dietary linoleate and arachidonate reduced the concentration of octadecenoic acid and increased that of stearic acid in the
mucosa and luminal lipids. This effect was prevented in the mucosa but not in the intestinal contents by antibiotic supplementation
of the linoleate diet.
Evidence for the conversion of linoleic into eicosatetraenoic acid was found in both mucosa and luminal lipids. The conversion
was impaired by the addition of antibiotics to the diet.
Linoleate feeding combined with antibiotic addition provided evidence for the intestinal hydrogenation of dietary linoleic
into either octadecenoic or stearic acids by separate routes, the latter being impaired by antibiotic ingestion.
The ingestion of methyl linoleate or arachidonate modified only slightly the fecal fatty acid pattern of rats previously on
a fat-free diet. 相似文献
13.
Jonathan A. Zerkowski 《Lipid Technology》2013,25(5):106-109
Spurred by improvements in catalysts as well as new experimental designs, lipid researchers have attained some impressive new outcomes by applying olefin metathesis to fatty acid substrates. Monomers for polyamides, environmentally‐responsive coatings, and blends of biofuels are among the bio‐derived materials obtained. This reaction is a powerful way to reconfigure the C18 skeleton into its component subunits such as alkenes or carboxylates, or to add functionality via a cross‐metathesis partner, thus continuing progress toward realizing the potential of plant oils as feedstocks for the biorefinery. 相似文献
14.
Copper oleate and cadmium oleate catalysts have been replaced by other metal compounds. Silver was the only metal which could
be substituted for copper in the ratio range studied. Using nickel oleate, the degree of saturation of the double bond decreased
with increasing cadmium oleate concentration. No comparable substitute was found for Cd. The composition of the final components
is influenced by the use of a paraffinic solvent, which also has an effect on the saturation of the double bond. An explanation
is given for the behavior of the catalyst when the reaction is not selective and is carried out in a paraffinic solvent. The
catalytic system Ag/Cd soaps was also studied kinetically and analytically. The results show that the mechanism of the reaction
using silver soap is identical with the one using copper soap. 相似文献
15.
M. J. Diamond R. G. Binder T. H. Applewhite 《Journal of the American Oil Chemists' Society》1965,42(10):882-884
The effects of temperature and media on the fusion of ricinoleic and lesquerolic acid derivatives with concentrated aqueous
alkali were examined. Improved yields ofω-hydroxy acids were obtained by use of excess 2-octanol. The effect of excess 2-octanol is discussed in relation to a recently
proposed reaction mechanism.
A laboratory of the W. Utiliz. Res. Devel. Div., ARS, USDA. 相似文献
16.
T. A. Foglia P. A. Barr A. J. Malloy M. J. Costanzo 《Journal of the American Oil Chemists' Society》1977,54(11):A870-A872
The oxidation of the alkali metal salts of oleic and undecylenic acid with ruthenium and osmium tetroxides is reported. The oxidants are used in catalytic amounts in conjunction with an excess of the in-expensive cooxidant sodium hypochlorite. Ruthenium tetroxide cleaves the carbon-carbon double bond of potassium oleate, to give pelargonic and gives sebacic acid. With osmium tetroxide, hydroxylation of the double bond of potassium oleate gives a 95% yield oferythro-9,10-dihydroxystearic acid. The osmium tetroxide oxidation of sodium undecylenate results in the formation of 10,11-dihydroxyundecanoic acid and the cleavage product sebacic acid in varying yields. 相似文献
17.
A. Gangadhar R. Subbarao G. Lakshminarayana 《Journal of the American Oil Chemists' Society》1984,61(7):1239-1241
Hydroxylamine has been recently found to react with ethyl acetate to generate diimide in situ. This reaction was used to reduce
10-undecenoic, oleic, linoleic, stearolic, concentrates of ricinoleic, cyclopentene and cyclopropene fatty acids (FA), dehydrated
castor oil FA, 10-undecen-1-ol, oleyl alcohol and castor fatty alcohols. Unsaturated FA and their corresponding alcohols reacted
in a similar manner. Terminally unsaturated, cyclopropene and cyclopentene FA were more reactive than oleic acid, which, in
turn, was more reactive than hydroxymonoenoic acids. Conjugated dienoic FA reduced faster than nonconjugated dienoic acids.
Partial hydrogenation using this reagent is particularly advantageous in determining geometry and the position of double bonds
in the polyunsaturated FA, as it can be carried out in the absence of oxygen or oxidizing agents unlike hydrazine reductions. 相似文献
18.
William R. Kidwell John Shaffer 《Journal of the American Oil Chemists' Society》1984,61(12):1900-1904
Studies with experimental animals first showed that dietary lipids in excess have a very large stimulatory effect on the development
of breast tumors either induced by carcinogens or occurring spontaneously. These observations took on added significance when
epidemiologists found a strong positive correlation between breast cancer incidence and the level of dietary fat. Although
not unequivocably established, the total observations concerning this phenomenon suggest a cause and effect relationship between
high dietary lipids and breast cancer development. In an attempt to understand how the lipids might be acting, we have begun
to assess the effects of various fatty acids on the growth and function of breast epithelium from both normal and neoplastic
tissue. The results to date suggest that the unsaturated fatty acids are needed for mammary cell division and that they may
play roles in this process by serving as substrates for prostaglandin synthesis, as membrane structural elements or possibly
as activators of C kinase when they are in the form of diglycerides. Whatever the mechanism of growth stimulation, it appears
that the fatty acids are rate limiting for growth and that physiologic mechanisms for recruiting fatty acids from proximal
fat cells exist within the mammary gland. It thus appears that the fat cell serves as a physiologic buffer and that exceeding
this buffer such as by consuming excessive lipids may override this buffering capacity and thus favor the division of normal
or neoplastic breast cells. 相似文献
19.
Schizochytrium sp. is a marine microalga that has been developed as a commercial source for docosahexaenoic acid (DHA, C22∶6 ω−3), enriched
biomass, and oil. Previous work suggested that the DHA, as well as docosapentaenoic acid (DPA, C22∶5 ω−6), that accumulate
in Schizochytrium are products of a multi-subunit polyunsaturated fatty acid (PUFA) synthase (1). Here we show data to support this view and
also provide information of other aspects of fatty acid synthesis in this organism. Three genes encoding subunits of the PUFA
synthase were isolated from genomic DNA and expressed in E. coli along with an essential accessory gene encoding a phosphopantetheinyl transferase (PPTase). The resulting transformants accumulated
both DHA and DPA. The ratio of DHA to DPA was approximately the same as that observed in Schizochytrium. Treatment of Schizochytrium cells with certain levels of cerulenin resulted in inhibition of 14C acetate incorporation into short chain fatty acids without affecting labeling of PUFAs, indicating distinct biosynthetic
pathways. A single large gene encoding the presumed short chain fatty acid synthase (FAS) was cloned and sequenced. Based
on sequence homology and domain organization, the Schizochytrium FAS resembles a fusion of fungal FAS β and α subunits. 相似文献
20.
The addition of glyoxylic acid ethyl ester to unsaturated fatty acid derivatives occurs with a maximum yield of 89%. The products are the corresponding 1:1-adducts. Temperature, reaction time, stoichiometry, and the concentration of the fatty acid derivative were investigated and optimized. A maximum yield was obtained with a fourfold excess of oleic acid ethyl ester, a reaction temperature of 200 °C, a reaction time of 24 h, and an oleic acid ethyl ester concentration of 1.3 mol/l. 相似文献