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1.
Jun Nagai Hirohiko Katsuki Yoshiki Nishikawa Ichiro Nakamura Teijiro Kamihara Saburo Fukui 《Biochemical and biophysical research communications》1974,60(2):555-560
The level of sterols in 4228 cells grown aerobically on a synthetic medium fortified with thiamine was significantly low compared with that in the control cells. The levels of free and esterified sterols in the thiamine-cells were 60% and 10% of the corresponding sterol levels in the control cells, respectively. Analysis by gas-liquid chromatography of non-saponifiable lipids extracted from the cells revealed that the amounts of squalene, lanosterol and two unidentified sterols were higher than those in the control cells and that ergosterol and zymosterol, major sterols in the control cells, were not present. These effects of thiamine on the content and composition of sterols were abolished by the addition of pyridoxine to the medium. 相似文献
2.
The sterol mixture isolated from the marine alga consists mainly of Δ5,7-dienes which account for 80% of the free sterols. Eighteen different sterols were detected, including a novel sterol with the rare Δ23-unsaturation, viz. 24-ethylcholesta-5,7,23Z-trien-3β-ol. 相似文献
3.
The effect of altered membrane sterol composition on the temperature dependence of yeast mitochondrial ATPase 总被引:8,自引:0,他引:8
The sterol content of cells of was manipulated by growing the organism anaerobically in a medium containing excess supplements of unsaturated fatty acids and a range of supplements of ergosterol. Anaerobic mitochondrial precursor structures were isolated whose membrane lipids contain the same fatty acid composition but whose sterol content varies from 7 to 105 mg/g mitochondrial protein. Arrhenius plots of the mitochondrial ATPase activity of the different preparations show a discontinuity with Arrhenius activation energies of about +40 and +80 KJ/mole, respectively, above and below the transition temperature. However, the temperature of the transition is markedly dependent on sterol composition, and increases by up to 17° as the sterol content of the mitochondria is progressively decreased. These results support the concepts that membrane lipid composition influences the activity of membrane-bound enzymes, and that sterols promote the gel to liquid phase transition in biological membranes. 相似文献
4.
More than thirty monohydroxy sterols were detected in the marine sponge , ranging from the ubiquitous 24-norcholesta-5, 22-dien-3β-o1 to the C30 sterol, 24-propylidenecholesterol. A new minor sterol was isolated and shown by spectral analysis and comparison with a synthetic sample to be (24R)-24,26-dimethy1cho1esta-5,26-dien-3β-o1 [26(29)-dehydroap1ysterol] (). 相似文献
5.
Eighteen components of the sterol fraction of have been identified. In addition to 4α-methyl sterols (typical dinoflagellate sterols), regular sterols, both with a saturated and Δ5-unsaturated skeleton, were isolated, together with Δ4-3-keto steroids including the hitherto unknown 23,24R-dimethyl-4,22E-cholestadien-3-one. 相似文献
6.
The lipid fraction of a Black Sea sponge, , was investigated for its sterol composition. Twenty-three sterols were identified, including the hitherto unknown 24-methyl-5α-cholesta-7, 9(11), 24(28)-trien-3β-ol (). Identification and structure elucidation were based upon 360 MHz 1H-NMR and MS analyses. 相似文献
7.
The complex sterol mixture isolated from was found to contain a low level of Δ4-3-keto steroids, 5β-stanols and 4α-methyl sterols in addition to regular (4-demethyl) sterols. The following new marine sterols were isolated and identified using MS and 360 MHz NMR: 5β-cholest-22E-en-3β-ol, 24S-methyl-5β-cholest-22E-en-3β-ol, 24-methylene-5β-cholestan-3β-ol, both epimers at C-24 of 4α-methyl-24-ethyl-5α-cholest-22E-en-3β-ol, 4α, 22ξ, 23ξ-(or 24ξ-)trimethyl-5α-cholest-8(14)-en-3β-ol and (22S, 23S, 24S)-4α-24-dimethyl-22, 23-methylene-5α-cholestan-3β-ol. The latter sterol and 23-demethylgorqosterol have opposite configurations at C-22, C-23, and C-24; the Δ8(14) sterol has an unprecedented side chain. 相似文献
8.
Several cholesterol analogs structurally modified in nuclear substitutions were tested for sustaining the growth of the silkworm . 5α-Cholest-7-en-3β-ol, 5,7-cholestadien-3β-ol and cholesteryl acetate can replace cholesterol as sterol source for Considerably good growth was also obained with 5α-cholest-14-en-3β-ol and 5α-cholesta-6,8(14)-dien-3β-ol. Other sterols tested were either partially effective or ineffective as nutrients. 相似文献
9.
J.L. Boutry M. Barbier M. Ricard 《Journal of experimental marine biology and ecology》1976,21(1):69-74
12-day cultures of the diatom Chaetoceros simplex calcitrans Paulsen in sea water have been analysed under different conditions of light. With a photophase the primary production is 106 % higher than under continuous light but the unsaponifiable fraction is lower (?42 %) and the sterols increase by 100 %. When ultra-violet irradiation is added to the photophase the primary production is lowered (?56 %) but the unsaponifiable fraction increases by 191 %, and the sterols by 110 %. When ultra-violet irradiation is added to the continuous light there is an increase in primary production (+30 %) and a decrease in the unsaponifiable fraction (?16%).Modifications of the sterol composition are reported. C26 sterols have never been detected in these experiments. 相似文献
10.
E. Fattorusso V. Lanzotti S. Magno E. Novellino 《Biochemical Systematics and Ecology》1985,13(2):167-168
The distribution of sterols in four Mediterranean hydroids has been examined. Cholesterol is the principal sterol in these organisms which uniquely contain , including a rather uncommon C26 compound. 相似文献
11.
The dinoflagellate was investigated for its sterol composition. Five of the six sterols were isolated and identified as cholest-5-en-3β-ol, (24ξ)-24-methylcholest-5-en-3β-ol, stigmasta-5,22-dien-3β-ol, (22E,24R)-4α,23,24-trimethyl-5α-cholest-22-en-3β-ol, and 4α,23ξ,24ξ-trimethyl-5α-cholestan-3β-ol. 相似文献
12.
Occelasterol, a new marine C27 sterol, has been isolated from an annelida, and its structure was confirmed as 22--27-nor-(24S)-24-methylcholesta-5, 22-dien-3β-ol (IIa) from the spectral data and by synthesis. Thissterol, the second member of a class of sterols having 27-norergostane-type side chain, had been formerly regarded as 22--cholesta-5, 22-dien-3β-ol (Va). Gas-liquid Chromatographic studies have shown that occelasterol is distributed in various amounts in most of marine invertebrates. 相似文献
13.
A mass spectrometric procedure which utilizes multiple selected ion monitoring (SIM) for measuring the tissue levels of cholest-5-en-3β,7α-diol, cholest-5-en-3β,7β-diol, cholest-5-en-3β,25-diol, and cholest-5-en-3β-ol-7-one is described. Trimethylsilyl ethers (TMS) of sterols in a lipid extract are analyzed directly by focusing the ions at 546, 472, and 443. Endogenous cholesterol serves as an internal standard and its concentration is determined by gas chromatography. The sensitivity of this method has allowed measurement of 2 ng of oxygenated sterol which corresponded to the amount present in 1 mg of rat liver. 相似文献
14.
Thomas M. Buttke Konrad Bloch 《Biochemical and biophysical research communications》1980,92(1):229-236
Under anaerobic growth conditions the isomeric 4,4′,14-trimethylcholestane derivatives lanosterol and, more efficiently, cycloartenol satisfy the sterol requirement of the yeast sterol auxotroph strain GL7. Aerobic mutant growth is supported only by cycloartenol and not by lanosterol, suggesting different structural requirements for aerobic and anaerobic cells. It is proposed that the non-planar conformation imposed by the 9,19-cyclopropane ring of cycloartenol moderates the adverse membrane effects of the nuclear methyl groups at C-4 and C-14. Under both aerobic and anaerobic conditions cyclolaudenol, a C-24-methyl derivative of cycloartenol, is a significantly more effective sterol source for strain GL7 than cycloartenol. This result is in keeping with the predominance of C-24-methyl sterols (ergosterol) in wild-type yeast. 相似文献
15.
Charge-pulse relaxation experiments with the negatively charged lipophilic ions, dipicrylamine and tetraphenylborate, (as well as with the positively charged carrier system Rb+-valinomycin) have been carried out in order to study the influence of sterols on the ion transport through the lipid bilayer membrane. The mol fraction of the sterols (cholesterol, epicholesterol, ergosterol, stigmasterol, dihydrocholsterol, epicoprostanol and cholesterololeate) as referred to total lipid was varied in a wide range (mol fractions 0–0.8).The monoolein/sterol or dioleoylphosphatidylcholine/sterol mixtures were dissolved in -hexadecane in order to minimize effects of the sterol on the membrane thickness.Cholesterol had a strong influence on the transport of the lipophilic ions. Its incorporation into monoolein membranes increased the rate constant of translocation up to 8-fold, but incorporation into phosphatidylcholine membranes had virtually no influence on . The other sterols with one hydroxy group and cholesterololeate had no influence on the rate constant or the partition coefficient β. The results are discussed on the basis of a possible change of dipole potential of the membrane caused by cholesterol and its derivatives.In the case of valinomycin-mediated Rb+ transport only cholesterol had a strong influence on transport properties. The rate constants of association () as well as the rate constants of translocation of the complex () and of the free carrier () were reduced by incorporation of cholesterol up to eight-fold. The decrease of and are possibly caused by a decrease of membrane fluidity, whereas the decrease of may be due to an increase of surface potential. The different action of cholesterol on the two transport systems is discussed under the assumption that the adsorption plane of the lipophilic ion is located more towards the aqueous side and that of the ion-carrier complexes more towards the hydrocarbon side of the dipole layer. 相似文献
16.
Almost an of the solvent-extractable sterols and their nuclearsaturated analogues in a sample of Walvis Bay surface sediment have been analysed by capillary GLC and GC-MS, and by coinjection with a variety of standards. The presence in sediments of 22--24-nor-5α-cholest-22-en-3β-ol, 24-methylene-5α-cholestan-3β-ol, and components tentatively assigned as 23,24-dimethylcholesta-5,22-dien-3β-ol and 23,24-dimethyl-5α-cholest-22-en-3β-ol has been demonstrated for the first time. A novel sterol and its saturated analogue have also been found. The sterol distribution cannot be related solely to the reported major input of phytoplankton; the presence of 22,23-methylene-23,24-dimethylcholest-5-en-3β-ol and its saturated analogue indicates a coelenterate contribution. The analysis emphasises the necessity of glass capillary columns and coinjection of standards. 相似文献
17.
Kernels were collected from three maize (Zea mays L.) inbreds from 10 days after pollination until kernel maturity. Sitosterol, campesterol, and stigmasterol were the major sterols at all stages of kernel development. Cholesterol was less than 1% of the dry weight. The three major sterols accumulated during kernel development, but at a rate slower than dry weight. The ratio of the sterols did not vary greatly among the inbreds. At maturity, the three inbreds, Wf9, Oh43, and Ky226, had sterol levels of 325, 228, and 173 micrograms per kernel, respectively. Sitosterol accounted for 75 to 85% of the sterol. The relative amount of stigmasterol decreased during the linear phase of development, while sitosterol increased in the free fraction and campesterol increased in the steryl ester fraction. 相似文献
18.
Leukemic guinea pig lymphocytes (L2 C) synthesise cholesterol in vitro at a forty-fold greater rate than normal cells. Equilibration (18 h) with lecithin or lecithin-cholesterol liposomes, respectively, enhances or suppresses sterol manufacture by normal lymphocytes but does not influence sterol production by L2 C cells. In contrast, molecules/cell of a nitroxide-derivative of androstane, (17 β-hydroxy-4′,4′-dimethylspiro [5 α-androstan-3,2′-oxazolidin]-3′-yloxyl), commonly used as a membrane spin-probe, drastically inhibit sterol production by both normal and leukemic cells (maximum within 2 h). At molecules/cell, this sterol stimulates cholesterol synthesis. 25-Hydroxycholesterol at low concentrations also stimulates sterol manufacture, whereas high concentrations are also inhibitory in both cell types. 相似文献
19.
The effects of estradiol-17β treatment on plasma lipid levels, liver lipid and glycogen reserves were examined during different phases of the reproductive cycle in goldfish, . Estrogen therapy resulted in increased plasma and hepatic lipid levels except during the spawning season. Hepatic glycogen deposits were depleted by estradiol injections during all seasons. Treatment of fish with the estrogen antagonist, CI-628, during the spawning season caused a reduction in plasma and liver lipid levels. Electrophoretic studies conducted during the post-spawning season showed that estrogen induces the appearance of a specific lipoprotein, probably a yolk precursor, in the serum and liver of goldfish. 相似文献
20.
A possible role for cytochrome P-450 during the biosynthesis of zymosterol from lanosterol by Saccharomyces cerevisiae 总被引:1,自引:0,他引:1
K T Alexander K A Mitropoulos G F Gibbons 《Biochemical and biophysical research communications》1974,60(1):460-467
A cell-free system has been obtained from which is capable of efficiently converting lanosterol1 to a mixture of 4-demethyl sterols, quantitatively the most important identifiable component of which was zymosterol. Little or no ergosterol was synthesized. In the presence of carbon monoxide, the rate of zymosterol biosynthesis from lanosterol was decreased by 57% compared with that observed in control incubations and the amount of unmetabolized lanosterol was greater. Mitochondrial electron transport inhibitors such as cyanide and antimycin A had no effect on the overall rate of 4-demethyl sterol biosynthesis from lanosterol nor on the degree of inhibition by carbon monoxide. 相似文献