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1.
Montanaro MA Rimoldi OJ Igal RA Montenegro S Tarrés MC Martínez SM Brenner RR 《Lipids》2003,38(8):827-832
Both diabetes mellitus type 1 and diabetes mellitus type 2 are widespread diseases that alter carbohydrate and lipid metabolism.
e Stilmann-Salgado (eSS) rats are experimental animals that spontaneously evolve to a state similar to that of young people
affected by non-insulin-dependent diabetes mellitus (NIDDM; type 2). Using 6-mon-old eSS rats that, according to the literature
[Martinez, S.M., Tarrés, M.C., Montenegro, S, Milo, R., Picena, J.C., Figueroa, N., and Rabasa, S.R. (1988) Spontaneous Diabetes
in eSS Rats, Acta Diabetol. Lat. 25, 303–313], had already developed insulin resistance, we investigated the changes evoked on Δ9, Δ6, and Δ5 liver desaturases.
The abundance of mRNA and enzymatic activities were measured, as well as the FA composition of liver microsomal lipids. Compared
to control rats, the mRNA content and activity of SCD-1 (stearoyl CoA-desaturase, isoform of the Δ9 desaturase) were significantly
higher, urase, isoform of the Δ9 desaturase) were significantly higher, whereas the mRNA and activities of Δ6 and Δ5 desaturases
were not significantly modified. Correspondingly, the proportion of 18∶1n−9 and the ratios of 18∶1n−9/18∶0 and 16∶1/16∶0 in
lipids were significantly increased, whereas the proportion of 20∶4n−6 was unaltered. These effects were found while glycemia
was constant or increased. The results are completely opposite those described in insulin-dependent diabetes mellitus (type
1), in which a depression of all the desaturases is found. They suggest that in eSS rats, the activities of the desaturases
were not modified by an insulin-resistance effect. Moreover, we suggest that the enhancement of SCD-1 activity might be considered
as another typical sign of the NIDDM syndrome, because it has also been found in other animal models of NIDDM, for example,
the ones evoked by the sucrose-rich diet and in the Zucker rat. 相似文献
2.
Acid-catalyzed isomerization of fucosterol and Δ5-avenasterol 总被引:1,自引:0,他引:1
Afaf Kamal-Eldin Kaisu Määttä Jari Toivo Anna-Maija Lampi Vieno Piironen 《Lipids》1998,33(11):1073-1077
This work shows that fucosterol, Δ5-avenasterol, and similar ethylidene-side chain sterols can undergo acid-catalyzed isomerization to give a mixture of five
isomers. Four isomers formed from fucosterol were analyzed, using gas chromatography-mass spectrometry, and were characterized
as Δ5-avenasterol two Δ5,23-stigmastadienols, and Δ5,24(250)-stigmastadienol. When the unsaponifiables fraction from oat oil was subjected to acid hydrolysis, the two Δ5,23-stigmastadienol isomers and Δ5,24(25)-stigmastadienol were detected while fucosterol coeluted with sitosterol. Interisomerization of ethylidene-side chain sterols
represents a limitation to the use of the acid hydrolysis method in the determination of sterols in food and other plant materials
rich in these sterols, e.g., oat lipids. 相似文献
3.
Although ω3‐ and ω6‐ desaturases have been well studied in terms of substrate preference and regiospecificity, relatively little is known about the membrane‐bound, “front‐end” long chain fatty acid desaturases, such as ?4, Δ5 or Δ6 desaturases. The first vertebrate ?4 desaturase was recently identified in the marine teleost fish Siganus canaliculatus (S. canaliculatus), which also possesses a bifunctional Δ5/6 desaturase. These two long chain polyunsaturated fatty acid desaturases are very different in terms of regiospecificity and substrate chain‐length, but share an unusually high degree of amino acid identity (83 %). We took advantage of this similarity by constructing a series of chimeric enzymes, replacing regions of one enzyme with the corresponding sequence of the other. Heterologous expression of the chimeric series of enzymes in yeast indicated that the substitution of a four amino acid region was sufficient to convert a ?4 desaturase to an enzyme with ?6 desaturase activity, and convert a ?5/6 desaturase to an enzyme with a low level of ?4 desaturase activity. In addition, enzymes having both ?4 and ?6 desaturase activities were produced by single or double amino acid substitutions within this four‐amino acid region. 相似文献
4.
Several properties of the compound 3,4-dihydro-2H-pyrrole(A1-pyrroline), which has been reported as a component of the male-produced Mediterranean fruit fly pheromone, have been determined by [1H]- and [13C]nuclear magnetic resonance spectroscopy. The stability of 1-pyrroline in several solvents and at moderately elevated temperatures has been investigated, and it has been established that it exists as both a monomer and trimer in solution. Although equilibrium studies indicate that the trimer is thermodynamically more stable than the monomer in solution, only the monomer was found in the vapor phase based on infrared analysis.This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or recommendation for its use by USDA. 相似文献
5.
Cloning of Δ12- and Δ6-desaturases from Mortierella alpina and recombinant production of γ-linolenic acid in Saccharomyces cerevisiae 总被引:2,自引:0,他引:2
Yung-Sheng Huang Sunita Chaudhary Jennifer M. Thurmond Emil G. Bobik Jr. Ling Yuan George M. Chan Stephen J. Kirchner Pradip Mukerji Deborah S. Knutzon 《Lipids》1999,34(7):649-659
Two cDNA clones with homology to known desaturase genes were isolated from the fungus Mortierella alpina. The open reading frame in one clone encoded 399 amino acids and exhibited Δ12-desaturase activity when expressed in Saccharomyces cerevisiae in the presence of endogenous fatty acid substrate oleic acid. The insert in another clone contained an open reading frame
encoding 457 amino acids and exhibited Δ6-desaturase activity in S. cerevisiae in the presence of exogenous fatty acid substrate linoleic acid. Expression of the Δ12-desaturase gene under appropriate
media and temperature conditions led to the production of linoleic acid at levels up to 25% of the total fatty acids in yeast.
When linoleic acid was provided as an exogenous substrate to the yeast cultures expressing the Δ6-desaturase activity, the
level of γ-linolenic acid reached 10% of the total yeast fatty acids. Co-expression of both the Δ6- and Δ12-desaturase cDNA
resulted in the endogenous production of γ-linolenic acid. The yields of γ-linolenic acid reached as high as 8% of total fatty
acids in yeast. 相似文献
6.
The freshwater microalga Parietochloris incisa accumulates, under nitrogen starvation, large amounts of triacylglycerols containing approximately 60% of the ω6 very long-chain
polyunsaturated fatty acid (VLC-PUFA), arachidonic acid. Based on sequence homology, we isolated three cDNA sequences from
P. incisa, designated PiDesD12, PiDesD6, PiDesD5. The deduced amino acid sequences of the three genes contained three conserved histidine motifs; the front-end desaturases,
PiDes6 and PiDes5, contained a fused N-terminal cytochrome b5 domain. By functional characterization in the yeast Saccharomyces cerevisiae, we confirmed that PiDesD6, PiDesD5 cDNA encode membrane bound desaturases with Δ6, and Δ5 activity, respectively. Both PiDes6 and PiDes5 can indiscriminately
desaturate both ω6 and ω3 substrates. A phylogenetic analysis showed that the three genes were homologous to the corresponding
desaturases from green microalgae and lower plants that were functionally characterized. Quantitative real-time PCR revealed
the concerted expression pattern of all three genes in P. incisa cells subjected to nitrogen starvation, featuring maximum expression level on day 3 of starvation, corresponding to the sharpest
increase in the share of arachidonic acid. 相似文献
7.
Helene Perrotin-Brunel Pablo Cabeza Perez Jaap van Spronsen Cor J. Peters 《The Journal of Supercritical Fluids》2010,52(1):6-719
The solubility of Δ9-tetrahydrocannabinol (Δ9-THC) in supercritical carbon dioxide has been determined at 315, 327, 334 and 345 K and in the pressure range from 13.2 to 25.1 MPa using an analytical method with a quasi-flow apparatus. Prior to performing these measurements, the method was validated by measuring anthracene solubilities and comparing these with literature values. The molar solubility for Δ9-THC ranged from 0.20 to 2.95 × 10−4. The data were correlated using the Peng-Robinson equation of state in combination with quadratic mixing rules. Deviations between calculated results and the experimental data ranged from 4.1 to 13.3% absolute average relative deviation (AARD). 相似文献
8.
Nozomu Kamada Hiroshi Kawashima Eiji Sakuradani Kengo Akimoto Jun Ogawa Sakayu Shimizu 《Journal of the American Oil Chemists' Society》1999,76(11):1269-1274
The Δ5 and Δ12 desaturase (DS)-blocked mutants of an arachidonic acid-producing fungus, Mortierella alpina 1S-4, were obtained. These mutants accumulated 8,11-cis-eicosadienoic acid (20:2n-9). One of the mutants, M226-9, in which Δ5 and Δ12 DS are perfectly blocked, produced 1.68 mg
of 20:2n-9 per mL of culture medium (101 mg/g dry mycelia) and no 5,8,11-cis-eicosatrienoic acid (20:3n-9) when grown in a medium containing 4% glucose and 1% yeast extract at 28°C for 2 d and then
at 12°C for 12 d. The mycelial lipid comprised 77.4% triacylglycerol (TG) and 9.8% phosphatidylcholine (PC), among others.
TG contained 69.0% of the total 20:2n-9, whose percentage in total TG fatty acids was 15.9%. The highest percentage (44.4%)
of 20:2n-9 was found in PC. The addition of olive oil to the culture medium enhanced the production of 20:2n-9. 相似文献
9.
Circular dichroism (CD) and deconvolution were used to study the structural integrity of a "plugged" and an "open" FhuA transmembrane channel protein in the presence of varied concentrations of tetrahydrofuran (THF), ethanol (EtOH) and chloroform/methanol (C/M). FhuA is an Escherichia coli outer membrane protein (78.9 kDa) consisting of 22 β-sheets and an internal globular cork domain which acts as an iron transporter. FhuA and the deletion variant FhuA Δ1-159 showed comparable and remarkable resistance in the presence of THF (≤40 vol%) and EtOH (≤10 vol%). In C/M, significant differences in structural resistance were observed (FhuA stable ≤10 vol%; FhuA Δ1-159 ≤1 vol%). Deconvolution of CD-spectra for FhuA and FhuA Δ1-159 yielded β-sheet contents of 61 % (FhuA) and 58% (FhuA Δ1-159). Interestingly, FhuA and FhuA Δ1-159 had comparable β-sheet contents in the presence and absence of all three organic cosolvents. Additionally, precipitated FhuA and FhuA Δ1-159 (in 40 vol% C/M or 65 vol% THF) redissolved by supplementing the detergent n-octyl-oligo-oxyethylene (oPOE). 相似文献
10.
Cats have limited Δ6 desaturase activity. However, γ-linolenate (GLA) feeding may by-pass the Δ6 desaturase step allowing
arachidonate (ARA) accumulation via Δ5-desaturation. Alternatively, high dietary linoleate (LNA) may induce limited Δ6 desaturase
also resulting in ARA accumulation. Fatty acid profiles were determined after feeding high LNA, high GLA, or adequate LNA
diets. Adult female cats (n = 29) were assigned to one of three groups and fed for 8 weeks. Plasma samples were collected at weeks 0, 2, 4 and 8 for
plasma triacylglycerol (TAG), total cholesterol (TC), lipoprotein (LP), and plasma and red blood cell membrane phospholipid
fatty acid determinations. Time, but no diet, effects were observed for TAG, TC, and LP fractions at weeks 2 and 4 with significant
increases likely due to increased dietary fat. However, all values were within feline normal limits. The GLA diet resulted
in increased dihomo-γ-linolenic acid (DGLA) and ARA as early as week 2, supporting a ∆5 desaturase. Further evidence of Δ5
desaturase was found at high dietary LNA with the appearance of a novel fatty acid, 20:3 ∆7, 11, 14, apparently formed via
∆5 desaturation and chain elongation of LNA. However, Δ6 desaturase induction at high dietary LNA concentration was not observed.
Cats are able to maintain plasma and red blood cell ARA when fed a practical diet containing GLA using what appears to be
an active Δ5 desaturase enzyme. 相似文献
11.
The Δ- and Λ-isomerism of octahedral metal complexes is employed as a source of chirality for inducing chiral nematic phases. By applying a wide range of chiral metal complexes as a dopant, it has been found that tris(β-diketonato)metal(III) complexes exhibit an extremely high value of helical twisting power. The mechanism of induction of the chiral nematic phase is postulated on the basis of a surface chirality model. The strategy for designing an efficient dopant is described, together with the results using a number of examples of Co(III), Cr(III) and Ru(III) complexes with C2 symmetry. The development of photo-responsive dopants to achieve the photo-induced structural change of liquid crystal by use of photo-isomerization of chiral metal complexes is also described. 相似文献
12.
Wolff RL Combe NA Destaillats F Boué C Precht D Molkentin J Entressangles B 《Lipids》2000,35(8):815-825
A survey of the total content of trans-18∶1 acids and their detailed profile in French food lipids was conducted in 1995–1996, and 1999. For this purpose, 37 food
items were chosen from their label indicating the presence of partially hydrogenated vegetable oils (PHVO) in their ingredients.
The content as well as the detailed profile of these isomers was established by a combination of argentation thin-layer chromatography
and gas-liquid chromatography (GLC) on long polar capillary columns. With regard to the mean trans-18∶1 acid contents of extracted PHVO, a significant decrease was observed between the two periods, i.e., from 26.9 to 11.8%
of total fatty acids. However, only minor differences were noted in the mean relative distribution profiles of individual
trans-18∶1 isomers with ethylenic bonds between positions Δ4 and Δ16 for the two periods. The predominant isomer was Δ9–18∶1 (elaidic)
acid, in the wide range 15.2–46.1% (mean, 27.9±7.2%) of total trans-18∶1 acids, with the Δ10 isomer ranked second, with a mean of 21.3% (range, 11.6 to 27.4%). The content of the unresolved
Δ6 to Δ8 isomer group was higher than the Δ11 isomer (vaccenic acid), representing on average 17.5 and 13.3%, respectively.
Other isomers Δ4, Δ5, Δ12, Δ13/Δ14, Δ15, and Δ16, were less than 10% each: 1.0, 1.6, 7.4, 7.1, 1.8, and 1.0%, respectively.
However, considering individual food items, it was noted that none of the extracted PHVO were identical to one another, indicating
a considerable diversity of such fats available to the food industry. A comparison of data for French foods with similar data
recently established for Germany indicates that no gross differences occur in PHVO used by food industries in both countries.
Estimates for the absolute mean consumption of individual isomers from ruminant fats and PHVO are made for the French population
and compared to similarly reconstructed hypothetical profiles for Germany and North America. Differences occur in the total
intake of trans-18∶1 acids, but most important, in individual trans-18∶1 isomer intake, with a particular increase of the Δ6–Δ8 to Δ10 isomers with increasing consumption of PHVO. It is inferred
from the present and earlier data that direct GLC of fatty acids is a faulty procedure that results (i) in variable underestimates
of total trans-18∶1 acids, (ii) in a loss of information as regards the assessment of individual isomeric trans-18∶1 acids, and (iii) in the impossibility of comparing data obtained from human tissues if the relative contribution of
dietary PHVO and ruminant fats is not known. 相似文献
13.
Patients with cystic fibrosis, caused by mutations in CFTR, exhibit specific and consistent alterations in the levels of particular
unsaturated fatty acids compared with healthy controls. Evidence suggests that these changes may play a role in the pathogenesis
of this disease. Among these abnormalities are increases in the levels of n-7 and n-9 fatty acids, particularly palmitoleate
(16:1n-7), oleate (18:1n-9), and eicosatrienoate or mead acid (20:3n-9). The underlying mechanisms of these particular changes
are unknown, but similar changes in the n-3 and n-6 fatty acid families have been correlated with increased expression of
fatty acid metabolic enzymes. This study demonstrated that cystic fibrosis cells in culture exhibit increased metabolism along
the metabolic pathways leading to 16:1n-7, 18:1n-9, and 20:3n-9 compared with wild-type cells. Furthermore, these changes
are accompanied by increased expression of the enzymes that produce these fatty acids, namely Δ5, Δ6, and Δ9 desaturases and
elongases 5 and 6. Taken together, these findings suggest that fatty acid abnormalities of the n-7 and n-9 series in cystic
fibrosis are as a result, at least in part, of increased expression and activity of these metabolic enzymes in CFTR-mutated
cells. 相似文献
14.
Hiroshi Kawashima Eiji Sakuradani Nozomu Kamada Kengo Akimoto Kyoko Konishi Jun Ogawa Sakayu Shimizu 《Journal of the American Oil Chemists' Society》1998,75(11):1495-1500
A Δ5 and Δ12 desaturase-defective mutant of an arachidonic acid-producing fungus, Mortierella alpina 1S-4, produced 8,11,14,17-cis-eicosatetraenoic acid (20:4ω3) intracellularly when grown with linseed oil. Dihomo-γ-linolenic acid was the only C20 polyunsaturated fatty acid (4.9 wt% of total mycelial fatty acids) other than 20:4ω3. AA and 5,8,11,14,17-cis-eicosapentaenoic acid were not detected. The mycelial lipids consisted of 82.2% (by mol) triacylglycerol (TG), 7.1% diacylglycerol,
8.9% phospholipids (PL), and 1.9% free fatty acids. The percentage of 20:4ω3 was higher in PL (30.1%) than in TG (11.6%),
and highest in phosphatidylcholine (38.9%). Under the optimal conditions with a 5-L jar fermenter, 20:4ω3 production amounted
to 97.4 mg/g dry mycelia with a mycelial yield of 23 g/L on the twelfth day (corresponding to 2.24 g/L medium and 37.1% of
total mycelial fatty acids). 相似文献
15.
The experimental determination of infinite dilution activity coefficients (γ∞) of liquid mixtures is carried out by gas chromatographic and ebulliometric techniques. Both methods show inaccuracies due to experimental difficulties.
This paper provides a comparative analysis of the influence of errors in measurements on the evaluation of γ∞ using ΔT — x and ΔP — x experimental data. It is shown that the errors in the determination of γ∞ from ΔP — x data are generally lower than those from ΔT — x ones 相似文献
16.
The Δ5-unsaturated polymethylene-interrupted fatty acid (Δ5-UPIFA) contents and profiles of gymnosperm seeds are useful chemometric
data for the taxonomy and phylogeny of that division, and these acids may also have some biomedical or nutritional applications.
We recapitulate here all data available on pine (Pinus; the largest genus in the family Pinaceae) seed fatty acid (SFA) compositions, including 28 unpublished compositions. This
overview encompasses 76 species, subspecies, and varieties, which is approximately one-half of all extant pines officially
recognized at these taxon levels. Qualitatively, the SFA from all pine species analyzed so far are identical. The genus Pinus is coherently united—but this qualitative feature can be extended to the whole family Pinaceae—by the presence of Δ5-UPIFA
with C18 [taxoleic (5,9–18∶2) and pinolenic (5,9,12–18∶3) acids] and C20 chains [5,11–20∶2, and sciadonic (5,11,14–20∶3) acids]. Not a single pine species was found so far with any of these acids
missing. Linoleic acid is almost always, except in a few cases, the prominent SFA, in the range 40–60% of total fatty acids.
The second habitual SFA is oleic acid, from 12 to 30%. Exceptions, however, occur, particularly in the Cembroides subsection, where oleic acid reaches ca. 45%, a value higher than that of linoleic acid. α-Linolenic acid, on the other hand, is a minor constituent of pine SFA,
almost always less than 1%, but that would reach 2.7% in one species (P. merkusii). The sum of saturated acids [16∶0 (major) and 18∶0 (minor) acids principally] is most often less than 10% of total SFA,
and anteiso-17∶0 acid is present in all species in amounts up to 0.3%. Regarding C18 Δ5-UPIFA, taxoleic acid reaches a maximum of 4.5% of total SFA, whereas pinolenic acid varies from 0.1 to 25.3%. The very
minor coniferonic (5,9,12,15–18∶4) acid is less than 0.2% in all species. The C20 elongation product of pinolenic acid, bishomo-pinolenic (7,11,14–20∶3) acid, is a frequent though minor SFA constituent (maximum,
0.7%). When considering C20 Δ5-UPIFA, a difference is noted between the subgenera Strobus and Pinus. In the former subgenus, 5,11–20∶2 and sciadonic acids are ≤0.3 and ≤1.9%, respectively, whereas in the latter subgenus,
they are most often ≥0.3 and ≥2.0%, respectively. The highest values for 5,11–20∶2 and sciadonic acids are 0.5% (many species)
and 7.0% (P. pinaster). The 5,11,14,17–20∶4 (juniperonic) acid is present occasionally in trace amounts. The highest level of total Δ5-UPIFA is
30–31% (P. sylvestris), and the lowest level is 0.6% (P. monophylla). Uniting as well as discriminating features that may complement the knowledge about the taxonomy and phylogeny of pines
are emphasized. 相似文献
17.
《Carbon》1987,25(4):469-475
For some graphitizable materials it is shown that after elimination of the skin effect, the ESR-line remains symetrically not only for d = δ but also for d <δ. For carefully prepared carbon samples the ESR-measurements allow the determination of the Δg-factor as well as the corrected Δg0-factor. A marked increase of the Δg-factor during the heat treatment of anthracene, phenanthrene and pyrene in the temperature range 1700–2400°C is observed. It is shown, that the Δg0-factor is a direct measure for the orientation degree (S) of the investigated material. An attempt is made to explain the shape of the observed ESR lines. 相似文献
18.
Amiram Raz Nurit Kamin-Belsky Fiorenza Przedecki Mark Obukowicz 《Journal of the American Oil Chemists' Society》1998,75(2):241-245
Liver Δ6-desaturase activity was determined in mice which were made deficient in (i) n-6 and n-3 polyunsaturated fatty acids
(PUFA), (ii) n-6 PUFA, or (iii) arachidonic acid (AA). Initially, the mice were subjected to two cycles of a fasting (1 d)/refeeding
(2–3 d) protocol in which they were refed an essential fatty acid-deficient (EFAD) diet during the refeeding period. This
1-wk fasting/refeeding protocol, referred to as F/R EFAD, produced a rapid and substantial decline in tissue n-3 and n-6 PUFA
and a corresponding increase in n-9 fatty acids, notably oleic acid and Mead acid (20:3n-9). Combined liver Δ6-desaturase/elongase/Δ5-desaturase
activities in vivo were quantified by measuring the conversion of 14C-linoleic acid (LA) to 14C-AA in mouse liver. Although F/R EFAD caused, as expected, a substantial decline in liver AA and LA content, the conversion
of 14C-LA to 14C-AA was the same in these mice as in chow-fed controls (approximately 33–34%). Subsequent refeeding of F/R EFAD mice with
an EFAD diet, supplemented with corn oil, restored tissue n-6 PUFA levels without altering the conversion of 14C-LA to 14C-AA. In contrast, refeeding with an EFAD diet, supplemented with fish oil, inhibited 14C-LA to 14C-AA conversion by 78%. Significantly, inhibition of conversion of 14C-LA to 14C-AA was maintained in F/R EFAD mice that were subsequently fed an EFAD diet supplemented with a 1:1 mixture of fish oil/corn
oil. This latter protocol yielded a unique liver fatty acid composition in which AA was selectively depleted, whereas LA and
the n-3 PUFA were increased. The data suggest that dietary n-3 C20–22 PUFA negatively regulate the in vivo synthesis of n-6 PUFA at the level of the Δ6-desaturase. 相似文献
19.
The triterpene alcohol fraction in several virgin olive oils and the corresponding oils refined by alkali and by physical
processes was analyzed by gas chromatography. A Δ7 compound was detected in all refined olive oils but not in virgin olive oils. This compound was tentatively identified by
gas chromatography-mass spectrometry as 24-methyl-5α-lanosta-7,24-dien-3β-ol, a 24-methylenecycloartanol isomer produced during
the refining process by the opening of the 9, 19 cyclopropane ring with formation of a double bond in the Δ7 position and the translocation of a double bond in the side chain from the 24–28 to the 24–25 position. 相似文献
20.
阐明Watson公式的不足和缺陷,应用分子热力学理论揭示出液体的汽化热取决于液体的分子间相互作用力,导出预测不同温度下有机纯质汽化热的新方程,其物理意义明确.经用39种结构类型的310个实验值检验,平均误差0.69%.Watson式为3.06%,本法的精度比Watson式高4.4倍以上. 相似文献