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1.
The activities of microsomal stearoyl-CoA desaturation, NADH-cytochrome b5 reductase, NADH-cytochrome c reductase, and the content of cytochrome b5 were similar in livers of normal and host rats. On the other hand, stearoyl-CoA desaturation activity was absent in Novikoff
hepatoma. The activities of NADH-cytochrome b5 and NADH-cytochrome c reductases in the hepatoma microsomes were 4.8% and 2.2%, respectively, of those in normal liver. Furthermore,
in hepatoma microsomes, cytochrome b5 was absent. An active stearoyl-CoA desaturation was reconstituted only on addition of both cytochrome b5 and the terminal desaturase enzyme to the hepatoma microsomes. These results indicated that a complete absence of cytochrome
b5 and terminal desaturase is responsible for the lack of stearoyl-CoA desaturation in Novikoff hepatoma microsomes. 相似文献
2.
Stearoyl-CoA desaturase activity in microsomes from lactating rat mammary gland is very low (0.05–0.15 nmol/min/mg of protein)
regardless of lactating time. In such microsomes, reductase activities and content of cytochrome b5 are several-fold lower than in normal rat liver microsomes. Preincubation of the mammary microsomes with purified terminal
desaturase gives a 55-fold stimulation of stearoyl-CoA desaturase activity, whereas preincubation with cytochrome b5 has no effect. However, preincubation of mammary microsomes with both cytochrome b5 and terminal desaturase results in a 200-fold stimulation of overall desaturation. These observations suggest that negligible
stearoyl-CoA desaturase activity in lactating rat mammary microsomes is due to a low cytochrome b5 content and the absence of terminal enzyme. The hepatic stearoyl-CoA desaturase activity increases 9-fold during lactation.
There is little or no change in the NADH-cytochrome c reductase activity or in the concentration of cytochrome b5 during this period, but the activity of the terminal desaturase increases with the increase of overall desaturation. These
results suggest that liver is one of the more important sources of oleic acid for milk triglycerides. 相似文献
3.
The microsomal stearoyl-CoA desaturase system was examined in both the Morris hepatoma 7288CTC, maintained in the host Buffalo
strain rat, and the Morris hepatoma 7288C, maintained in tissue culture. In vitro examination shows the stearoyl-CoA desaturase
system to be similar in the 2 tissues. Both show extremely low overall stearoyl-CoA desaturase activity, having 4% and 8%
of normal liver values respectively. Examination of the electron transport system showed both tissues have decreased electron
transport components cytochrome b5 and cytochrome b5 reductase. Particularly noticeable were the extremely low levels of cytochrome b5 (2% compared with normal liver). Microsomes from both tissues showed a decreased ability to reduce an artificial electron
acceptor, cytochrome c. With the low levels of cytochrome b5 observed in these tissues, the low levels of overall desaturase activity may be caused by lack of terminal enzyme, lack of
sufficient cytochrome b5, or both. Analysis of the stearoyl-CoA desaturase system in cultured hepatoma cells suggests that these cells are similar
to the host-grown tumor in this respect and may be used as a model in further examinations of the stearoyl-CoA desaturase
system. 相似文献
4.
We have examined the extent to which it is possible to modify the fatty acid composition of subcellular organelles of L1210
leukemia cells. A polyunsaturated fatty acid, docosahexaenoic acid, or a monounsaturated fatty acid, oleic acid, were added
to the culture media. After 48 hr, the cells were ruptured and the subcellular fractions isolated. Fatty acid analysis revealed
that nuclei, mitochondria, plasma membranes and microsomes of the cells grown in media supplemented with docosahexaenoic acid
contained increased amounts of polyenoic fatty acids, mean number of double bonds and docosahexaenoic acid compared with cells
grown in oleic acid. We conclude that it is possible to experimentally modify the lipids of multiple intracellular structures
of L1210 cells by the addition of fatty acids to the growth media. 相似文献
5.
Isomeric methyl esters of fatty acids in three groups (C15, C17, C19) have been isolated from ruminant fats. Basic structural analysis by physiochemical techniques indicated that these odd-numbered
fatty acids were even chain with a single methyl branch on the chain. High resolution open-tubular gas liquid chromatographic
studies indicate that, with the exception of iso acid impurities in these fractions, only even-numbered carbons of the fatty
acid chains bear the methyl branch. 相似文献
6.
Polyunsaturated fatty acids can be oxygenated by cytochrome P450 to hydroxy and epoxy fatty acids. Two major classes of hydroxy
fatty acids are formed by hydroxylation of the ω-side chain and by hydroxylation of bisallylic methylene carbons. Bisallylic
cytochrome P450-hydroxylases transform linoleic acid to 11-hydroxylinoleic acid, arachidonic acid to 13-hydroxyeicosa-5Z,8Z,11Z,14Z-tetraenoic
acid, 10-hydroxyeicosa-5Z,8Z,11Z,14Z-tetraenoic acid and 7-hydroxyeicosa-5Z,8Z,11Z,14Z-tetraenoic acid and eicosapentaenoic
acid to 16-hydroxyeicosa-5Z,8Z,11Z,14Z,17Z-pentaenoic acid, 13-hydroxyeicosa-5Z,8Z,11Z,14Z,17Z-pentaenoic acid and 10-hydroxyeicosa-5Z,8Z,11Z,14Z,17Z-pentaenoic
acid as major metabolites. The bisallylic hydroxy fatty acids are chemically unstable and decompose rapidly tocis-trans conjugated hydroxy fatty acids during acidic extractive isolation. Bisallylic hydroxylase activity appears to be augmented
in microsomes induced by the synthetic glucocorticoid dexamethasone and by some other agents, but the P450 gene families of
these hydroxylases have yet to be determined. The fatty acid epoxides, which are formed by cytochrome P450, are chemically
stable, but are hydrolyzed to diols by soluble epoxide hydrolases. Epoxidation of polyunsaturated fatty acids is a prominent
pathway of metabolism int he liver and the renal cortex and epoxygenase activity appears to be under homeostatic control in
the kidney. Many arachidonate epoxygenases have been identified belonging to the CYP2C gene subfamily. Epoxygenases have also
been found in the central nervous system, endocrine organs, the heart and endothelial cells. Epoxides of arachidonic acid
have been found to exert pharmacological effects on many cells. 相似文献
7.
Effect of dietary columbinic acid on the fatty acid composition and physical membrane properties of different tissues of EFA-deficient rats 总被引:1,自引:0,他引:1
The effect of columbinic acid (5 trans, 9 cis, 12 cis, octadeca-trienoic acid) supplemented to a fat-free diet on the fatty acid composition and its correlation to the physical properties of several tissues of rats, was studied. The absence of lipids in the diet produced the typical changes in the fatty acid composition characteristic of essential fatty acid (EFA) deficiency, namely a significant increase in the relative percentage of monoenoic fatty acids with a concomitant decrease in linoleic and arachidonic acids and a rise in eicosa-5,8,11-trienoic acid in liver, kidney, lung and spleen homogenates. Columbinic acid supplemented to a fat-free diet for 24 or 48 hr was incorporated into the different tissues and was partially elongated to 7 trans, 11 cis, 14 cis eicosatrienoic acid, but it was not desaturated. It modified the fatty acid spectrum of the lipids in the different tissues returning it to a similar composition of non-EFA deficient animals, except for a decrease of linoleic acid. The absence of lipids in the diet produced an increase in the 1-6 diphenyl-1,3,5-hexatriene (DPH) steady-state fluorescence anisotropy (rs) in liver microsomes, that was corrected by the administration of columbinic acid for 24 hr. It is concluded that columbinic acid produced a change in the pattern of total fatty acid composition of the different tissues studied which induced a favorable effect on the physical properties of the liver microsomal membranes (rs), leading to an improvement on the fatty acid deficiency in those membranes. Besides, columbinic acid would also exert a favorable effect in the short term, but not in the long-term eicosanoids production. 相似文献
8.
Female rats warm-adapted at 30–32 C for 20–25 days and then shifted to 13–15 C for 12, 24, 48, 72 and 120 hr showed that Δ9
desaturase and fatty acid synthetase activity decay after 24 hr of cold exposure, while Δ6 and Δ5 desaturases were increased
after this period of time. These results were confirmed by an increase of arachidonic acid of heart and liver microsomes phosphatidylcholine
and a decrease of oleic acid. Neither NADH-cyt b5 reductase nor NADH-cyt c reductase activity of liver microsomes were significantly affected. Male rats warm-adapted under
the same conditions and then shifted to 13–15 C for 120 hr did not show significant changes in fatty acid synthetase, Δ9 and
Δ6 desaturases and enzymes of the microsomal electron transport chain. Therefore, the desaturase response to environmental
temperature changes could be plausibly linked to female hormones. 相似文献
9.
Gotoh N Moroda K Watanabe H Yoshinaga K Tanaka M Mizobe H Ichioka K Tokairin S Wada S 《Journal of oleo science》2008,57(5):293-299
Fatty acids are converted into energy via beta-oxidation. Although almost all natural occurring fatty acids are even-numbered, there are some odd-numbered fatty acids too. The details of the metabolism rate of odd-numbered fatty acids, however, are not clear. In the present study, we simultaneously administered a triacylglycerol containing four types of labeled even-numbered (palmitic acid and stearic acid) and odd-numbered (pentadecanoic acid and heptadecanoic acid) fatty acids to mice to compare the rates of their metabolism. The rates of metabolism were evaluated based on the accumulation of the labeled fatty acids in the small intestine epithelium, liver, and epididymal fat. Odd-numbered fatty acids accumulated mainly in the epididymal fat. In contrast, there was no accumulation of even-numbered fatty acids observed in the small intestine epithelium, liver, or epididymal fat. These results suggest that odd-numbered fatty acids might not be favorable substrates for beta-oxidation-related enzymes. 相似文献
10.
Effects of growth hormone on phospholipid composition and fatty acyl distribution were studied in liver mitochondria of hypophysectomized
rats. After hypophysectomy, only cardiolipin showed a 25% decrease. Its fatty acyl distribution, which consisted mainly of
linoleic acid (55–60%) and oleic acid (20%), was unchanged. In phosphatidylcholine and phosphatidylethanolamine fractions
the contents of docosahexaenoic and arachidonic acids were decreased with a concomitant increase in linoleic acid content.
These changes could be accounted for by small but significant decreases in the activities of Δ9-desaturase (sucrose-induced), Δ5-desaturase and mitochondrial elongation enzymes. The activities of Δ6-desaturase NADH cytochrome b5 ferri-reductase, cytochrome b5, NADH cytochrome c reductase and microsomal elongation enzymes remained virtually unchanged. Injection of bovine growth hormone
daily for seven days restored cardiolipin and fatty acyl distribution and the enzyme activities. From these and other results,
we conclude that growth hormone-dependent increase of respiratory activity of liver mitochondria may be partly mediated by
the hormonal effects on membrane lipid distribution. 相似文献
11.
H. Hirono Ph.D. 《Lipids》1980,15(4):272-275
The lipid classes and fatty acid compositions of myelin, white matter and gray matter were analyzed in a case of generalized
deficiency of cytochrome b5 reductase in congenital methemoglobinemia with mental retardation. When compared with normal data, the percentage of 24∶1
was considerably decreased and diminished unsaturation was observed in cerebrosides, whereas the sum of 24∶0 and 24∶1 was
the same as in normals. The ratio of hydroxy fatty acids to total fatty acids in cerebrosides was low. The contents of cholesterol
and phospholipids in white matter were reduced to 80% of the normal, whereas cerebroside was reduced to 48% of the normal. 相似文献
12.
A total of fifteen saturated fatty acid esters were newly identified from the secretions of an unidentified Anaulaciulus sp. (Julida: Julidae). The fatty acid components of the esters were composed of normal chain acids (from C10 to C14) and of branched chain acids (from iso-C12 to iso-C15 and anteiso-C15). The alcohol moieties were all composed of normal chain alcohols varying from n-butanol to n-octanol. The most abundant component found in the total esters was n-hexyl laurate (64.7%). Novel compounds identified from the millipede secretion extracts include six branched iso- and anteiso-fatty
esters, an odd-numbered C11-fatty acid ester, a C13-fatty acid ester, and a C7-alcohol ester, all of which were previously undescribed natural products. In addition, a characteristic mixture of benzoquinones,
such as 2-methyl-1,4-benzoquinone, 2-methoxy-3-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, 2-methoxy-6-methyl-1,4-benzoquinone,
and 2,3-dimethoxy-5-methyl-1,4-benzoquinone were identified from the secretions, together with trace amounts of 1,4-benzoquinone. 相似文献
13.
Delta-6 and Δ5 desaturation activity of rat adrenal gland microsomes was studied to determine the effect of microsomal protein
and the substrate saturation curves. This tissue has a very active Δ6 desaturase for linoleic and α-linoleic acids and a Δ5
desaturase for eicosa-8,11,14-trienoic acid. The administration of epinephrine (1 mg/kg body weight) 12 hr before killing,
produced approximately a 50% decrease in desaturation of [1-14C]linoleic acid to γ-linolenic acid, [1-14C]α-linolenic acid to octadeca-6,9,12,15-tetraenoic acid and [1-14C]eicosa-8,11,14-trienoic acid to arachidonic acid. A 30% decrease in Δ5 desaturation activity was also shown after 7 hr of
epinephrine treatment. The changes on the oxidative desaturation of the same fatty acids in liver microsomes were similar.
No changes were observed in the total fatty acid composition of adrenal microsomes 12 hr after epinephrine treatment. Mechanisms
of action of the hormone on the biosynthesis of polyunsaturated fatty acids in the adrenal gland are discussed. 相似文献
14.
Edward Mascioli Lorraine Leader Enrique Flores Susan Trimbo Bruce Bistrian George Blackburn 《Lipids》1988,23(6):623-625
Improved survival to endotoxin has been demonstrated in rats pretreated with cyclooxygenase inhibitors or made essential fatty
acid deficient, implying that excessive ω6 fatty acids, possibly through their eicosanoid products, contribute to mortality.
Following endotoxin administration, we also have shown improvement in survival with oral diets supplemented with fish oil.
This study sought to explore whether parenteral fish oil ameliorates the adverse impact of endotoxin.
Male Hartley-strain guinea pigs were obtained at a body weight of 500 g and fed a normal laboratory diet. Central venous lines
through which the animals received either a 10% safflower oil emulsion (n=11) or a 10% fish oil emulsion (n=11) during two,
24-hr periods separated by two days were inserted. Two days after the second infusion, endotoxin (0.35 mg/100 g b.w.), was
given intraperitoneally, and survival was noted. The animals received a total of 25.4 g of IV fat per kg b.w., including 5.3
g of eicosapentaenoic acid per kg b.w., for the fish oil group.
From six hr after endotoxin through four days, there was better survival in the fish oil group (p<.006). Final mortality showed
7/11 fish-fed vs 2/11 safflower-fed animals surviving. We conclude that the administration of parenteral fish oil, even for
a brief time, can have a profound effect on subsequent survival to endotoxin. 相似文献
15.
The Fu5AH rat hepatoma cell line accumulates cholesteryl ester (CE) upon incubation in medium supplemented with hyperlipemic
serum or hyperlipemic serum lipoproteins. This cell line was used to investigate the origin of the fatty acids esterified
to cholesterol in intracellular accumulations of CE. The intracellular CE-fatty acid distribution was found to be markedly
different from that of the lipoprotein which stimulated the accumulation. Free fatty acids added to the culture medium were
found esterified to cholesterol in the cells, demonstrating that cellular esterification contributes to the accumulation of
CE. Using a subline of Fu5AH cells containing radioactively labeled intracellular fatty acids, it was found that about one-third
of the fatty acid moiety of CE accumulated by the cells during a 24 hr incubation with hyperlipemic serum was derived from
endogenous fatty acids. The drug chloroquine was found to inhibit cellular cholesterol esterification, so that only 4% of
CE-fatty acids were derived from endogenous fatty acids. Evidence is presented suggesting a major role for cellular esterification
in CE accumulation by Fu5AH cells. 相似文献
16.
The effect of dietary conjugated linoleic acid (CLA) supplementation in combination with fat from vegetable versus animal
origin on the fatty acid deposition, including that of individual 18:1 and 18:2 (conjugated and non-conjugated) isomers, in
the liver and muscle of obese rats was investigated. For this purpose, 32 male Zucker rats were randomly assigned to one of
four diets containing palm oil or ovine fat, supplemented or not with 1% of 1:1 cis(c)9,trans(t)11 and t10,c12 CLA isomers mixture. Total fatty acid content decreased in the liver and muscle of CLA-fed rats. In the liver, CLA increased
saturated fatty acids (SFA) in 11.9% and decreased monounsaturated fatty acids (MUFA) in 6.5%. n-3 Polyunsaturated fatty acids
(PUFA) relative proportions were increased in 30.6% by CLA when supplemented to the ovine fat diet. In the muscle, CLA did
not affect SFA but decreased MUFA and PUFA percentages. The estimation of Δ9-indices 16 and 18 suggested that CLA inhibited
the stearoyl-CoA desaturase activity in the liver (a decrease of 13–38%), in particular when supplemented to the ovine fat
diet. Concerning CLA supplementation, the t10,c12 isomer percentage was 60–80% higher in the muscle than in the liver. It is of relevance that rats fed ovine fat, containing
bio-formed CLA, had more c9,t11 CLA isomer deposited in both tissues than rats fed palm oil plus synthetic CLA. These results highlight the importance
to further clarify the biological effects of consuming foods naturally enriched in CLA, alternatively to CLA dietary supplementation. 相似文献
17.
K. Lusky M. Stoyke K.-D. Doberschütz R. Gbel 《European Journal of Lipid Science and Technology》1992,94(7):260-267
Investigations on the Influence of Odd-Numbered Fatty Acids on the Lipid Metabolism in Pigs Two groups of piglets (n=3) with life weights of 12.0 ± 1.4 kg were given feedstuff containing different mixtures of odd-numbered fatty acids. For comparison, a control group was given feedstuff of customary lipid composition. At the end of the test period, spinal fat, cardiac lipids, cerebral lipids, muscular lipids and hepatic lipids were analyzed. Contingent on the mixtures of odd-numbered fatty acids given, an enrichment of C18:2 was determined in the organic lipids as well as in the depot fat of the animals. In addition to saturated odd-numbered fatty acids, the corresponding unsaturated acids were also produced. Hence the enzymic system of pigs is capable of desaturating odd-numbered fatty acids. The determined concentrations of n-3 fatty acids were partly higher, partly lower. 相似文献
18.
Branched-chain fatty acids of perinephric triacylglycerols of semi-feral fallow deer (Dama dama dama) were analyzed by high resolution gas chromatography-mass spectrometry. Of the total fatty acids, 15.50% were Branched-chain
components including 8.96% iso acids, mostly 14-methylpentacanoic acid, 2.85% anteiso acids and 1.73% of other monomethyl-substituted
acids; dimethyl-branched acids with an iso structure (1.05%) and with an anteiso structure (0.18%) were also present. Whereas
the predominant iso acids and methyl-substituted iso acids had chain lengths of 13 and 15 carbon atoms, the anteiso acids
and methyl-substituted anteiso acids had chain lengths of 14 and 16 carbon atoms. Methyl substitution occurred on the even
numbered carbon atoms relative to the carboxyl group. The general composition is also given of the fatty acids comprising
the triacylglycerols of subcutaneous (rump area) and perinephric adipose tissue. 相似文献
19.
In this paper we present further evidence for the close control of fatty acid synthetase and stearoyl-CoA desaturase. Furthermore, we have established that whereas dietary palmitic acid may influence the activity of this desaturase but not of fatty acid synthetase, dietary linoleic acid appears to control both these enzymes. Finally, we have studied the influence of dietary fat and carbohydrate on the activities of the delta6 and delta5 desaturases. The former is only slightly affected by these dietary components. The delta5 desaturase activity is stimulated as the dietary fat content rises but is unaffected by dietary carbohydrate. The control of these enzymes is therefore independent of the control of fatty acid synthetase and stearoyl-CoA desaturase. From the data presented, the magnitude of the controlling effect of polyunsaturated fatty acids on fatty acid synthetase and stearoyl-CoA desaturase activity is determined and its relevance to lipogenesis in man based on daily intake of carbohydrate and linoleic acid is discussed. 相似文献
20.
Liver microsomes of the Japanese harvest mouse (Micromys minutus), which is the smallest known mammal among rodents, catalyze the hydroxylation of various fatty acids (C8 to C18) to the corresponding ω-hydroxy and (ω-1)-hydroxy derivatives. Although laurate is most effectively hydroxylated among saturated
fatty acids by liver microsomes of other species, harvest mouse liver microsomes most effectively catalyze the hydroxylation
of decanoate. From inhibitor and cofactor studies, and from the substrate specificity for hydroxylation, it was concluded
that ω- and (ω-1)-hydroxylation of fatty acids are catalyzed by different cytochrome P-450 species in the liver microsomes
of the harvest mouse. 相似文献