共查询到20条相似文献,搜索用时 15 毫秒
1.
Denis J. Murphy 《Lipids》1988,23(3):157-163
The subcellular distribution of the enzymes of triacylglycerol biosynthesis has been studied in developing oilseed rape. All
in vitro enzymatic activities from oleoyl-CoA to triacylglycerol were sufficient to account for the known rate of oleate deposition
in triacylglycerol in vivo. The enzymatic activities from oleoyl-CoA to diacylglycerol preferentially were localized in a
150,000 g supernatant fraction, while the diacylglycerol acyl-transferase mostly was associated with the microsomal (20,000
g pellet and 150,000 g pellet) and oil-body fractions. The soluble (150,000 g supernantant) fraction rapidly incorporated
oleate from [1-14C]oleoyl-CoA into diacylglycerol with rates of 40 nm min−1 g−1 FW at 20 μM oleoyl-CoA. The pH optimum was 7.5–9.0, and normal saturation kinetics were seen with oleoyl-CoA; the S0.5 was about 32 μM. Exogenous acyl acceptors, such as glycerol 3-phosphate, lysophosphatidic acid and lysophosphatidylcholine
stimulated oleate incorporation into diacylglycerol. The detergents Triton X-100 and sodium cholate inhibited diacylglycerol
formation at concentrations in the region of their critical micellar concentration, while n-octyl-β,D-glyco-pyranoside had
no effect, even at high concentration. The significance of these findings for the mechanism of oil-body formation in developing
oilseeds is discussed. 相似文献
2.
George V. Vahouny Robert Tombes Marie M. Cassidy David Kritchevsky Linda L. Gallo 《Lipids》1980,15(12):1012-1018
Mixed micelles were prepared containing combinations of either taurocholate or taurochenodeoxycholate, monoolein, oleic acid,
dioleylphosphatidylcholine (lecithin) and cholesterol. These were incubated with commercial bile-acid-sequestering resins,
cholestyramine and DEAE-Sephadex, or various dietary fibers and fiber components including wheat bran, cellulose, alfalfa,
lignin and 2 viscosity grades of guar gum. Binding was determined as the difference between the radioactivity of each micellar
component added and that recovered in the centrifugal supernatant after incubation. In general, the extent of bile salt sequestration
was characteristic and reproducible for each bile salt, and was largely unaffected by the presence of one or more additional
components of the micellar mixture, including the other bile salt. Cholestyramine bound 81–92% of the bile salts and 86–99%
of the phospholipid and cholesterol present in micelles. DEAE-Sephadex sequestered only 49% of the taurocholate and 84% of
the taurochenodeoxycholate, but completely removed all of the phospholipid and cholesterol from micelles containing either
bile salt. Among the dietary fibers, guar gum of either viscosity bound between 20–38% of each micellar component, whereas
lignin, alfalfa, wheat bran and cellulose were progressively less effective in sequestratin of individual components of mixed
micelles. The extent of sequestration of micellar components by these resins and fibers is reasonably correlated with the
effects of these same materials on lymphatic absorption of lipids and to their suggested hypocholesteremic properties. 相似文献
3.
The study of the effect of solutions of ammonium salts of low concentrations on polyester fibre material showed that modification
of the material with ammonia formed by thermal hydrolysis of ammonium salts differs from modification with ammonia obtained
by the reaction of equimolar quantities of ammonium nitrate and sodium hydroxide and is similar to the process that takes
place when ammonia is added to the working solution. Of the salts examined, ammonium fluoride in the concentration of 0.02–0.35
M at 130°C and 30-min process time is the most active modifying agent. In these conditions, ammonium fluoride and the products
of its high-temperature hydrolysis — hydrogen fluoride and ammonia — have the strongest catalytic effect on hydrolysis of
cyclic oligomers with formation of their linear form. On the whole, ammonium fluoride has a stronger modifying effect on polyester
material than aqueous ammonia.
__________
Translated from Khimicheskie Volokna, No. 1, pp. 17–21, January–February, 2007. 相似文献
4.
Hepatic biotransformation and the effect on bile flow of 7-ketolithocholic acid (7-oxo-3α-hydroxy-5β-cholan-24-oic acid),
in comparison to ursodeoxycholic acid, were examined in rats under conditions of continuous infusion of solutions of sodium
salts of these bile acids (1.2μmol/min/100 g body wt) for 2 hr. Both bile salts elevated the bile flow rate as well as the
bile bicarbonate concentration to a similar degree. The minor difference observed was a transient (10–20 min) and subtle drop
of bile flow during the first hour in rats given 7-ketolithocholate. In ursodeoxycholate infused rats, the major bile salt
in the bile was its taurine conjugate, although excretion of tauroursodeoxycholate dropped considerably during the second
hour. In 7-ketolithocholate infused rats, the major bile salt in the bile was again, its taurine conjugate, but ursodeoxycholate
and chenodeoxycholate and their conjugates were also excreted. In contrast to ursodeoxycholate infused rats, the drop in excretion
of taurine conjugates and the increase of glycine conjugates in rats infused with 7-ketolithocholate were more rapid. In rats
infused with 7-ketolithocholate, excretion of ursodeoxycholate and its conjugates was significantly higher than the corresponding
values for chenodeoxycholate, suggesting that 7-ketolithocholate is reduced predominatly to the 7β-epimer in this species.
However, the concentration of ursodeoxycholate and its conjugates excreted into the bile in rats infused with 7-ketolithocholate
was only 10% of that of rats infused with ursodeoxycholate, yet the magnitude of choleresis and the rise in bile bicarbonate
concentration were similar in both experiments. Therefore, it is suggested that the bicarbonate-rich bile, induced by 7-ketolithocholate
infusion, is caused mainly by 7-ketolithocholate rather than by its metabolite, ursodeoxycholate. 相似文献
5.
Synthesis and aqueous solution properties of aliphatic double chain end-capped poly(ethylene glycol)
Summary
A PEG-based amphiphilic polymer bearing two aliphatic double chain moieties was prepared. Its diluted aqueous solution properties
were studied by viscometry, dye solubilization and rheology. At concentrations lower than (6–8)×10−3 g/mL ring-shaped macromolecules were formed due to intrachain hydrophobic interactions. At concentrations about (6–8)×10−3 g/mL a formation of "flower" type aggregates took place. 1,6-Diphenyl-1,3,5-hexatriene solubilization was used to prove the
existence of hydrophobic domains and a critical aggregation concentration of 7×10−3 g/mL was determined. The peculiar viscosity profile and the rheopectic behavior of the amphiphilic polymer were attributed
to the existence of aggregates and to a temporary network formation during deformation, respectively.
Received: 13 February 2001/Revised version: 15 June 2001/Accepted: 15 June 2001 相似文献
6.
Dorota Johansson 《Journal of the American Oil Chemists' Society》1995,72(10):1235-1237
The formation of fat crystal gels in soybean oil has been studied by sedimentation in a low concentration region at 10–25°C.
At 10°C, weak gels were formed with 1% crystals, and no gels formed at concentrations of 2–5%. At temperatures of 15–25°C,
no gels were formed at concentrations of 1–5%, and samples sedimented. Stronger gels of fat crystals were formed with ∼10%
fat crystals at all temperatures examined. Formation of weak gels is a consequence of the fractal nature of fat crystal aggregates
and sediments. At low temperature, the interaction is weak. The fractal dimension is then high, and the floc size is large
for low crystal concentrations. These large flocs form a three-dimensional network that act as a weak gel and withstand gravitational
force. When the temperature is increased, the fat crystal interaction becomes stronger, fractal dimension decreases, and floc
size decreases. Smaller flocs have a higher density, pack more easily, and sediment. Similar effects are observed when the
concentration of fat crystals is increased at low temperature due to a decrease in floc size. 相似文献
7.
A methodology using stripping voltammetry has been elaborated to enable sensitive and reliable protein–chromium complexation
measurements. Disturbing effects caused by adsorption of proteins on the mercury electrode were addressed. At low concentrations
of proteins (<60–85 nM), chromium–protein complexation measurements were possible. Chromium(VI) complexation was quantitatively
determined using differently sized, charged, and structured proteins: serum albumin (human and bovine), lysozyme, and mucin.
Generated results showed a strong relation between complexation and protein size, concentration, and the number of amino acids
per protein mass. Complexation increased nonlinearly with increasing protein concentrations. The nature of this complexation
was based on weak interactions judged from combined results with MALDI-TOF–MS and adsorptive cathodic stripping voltammetry. 相似文献
8.
The high-performance liquid chromatographic separation and quantitation of conjugated bile salts from pig bile is reported.
Synthetic standards and bile samples were chromatographed on a C18 reversed phase column using acetonitrile/water/tetrabutyl ammonium phosphate as an isocratic mobile phase at a flow rate
of 1 mL/min. Detection of the ion-pairs was at 214 nm. The method permits efficient separation of all conjugated pig biliary
bile salts without prior modification or treatment of the samples. Analysis of 12 pig biles showed that 85% of the bile salts
are conjugated to glycine. The three main conjugated bile salts were glyco-3α,6α,7α-trihydroxy-5β-cholanoic acid (GHC), glyco-3α,7α-dihydroxy-5β-cholanoic
acid (GCDC), and glyco-3α,6α-dihydroxy-5β-cholanoic acid (GHDC). Glyco-3α-hydroxy-6-oxo-5β-cholanoic acid (G3α6oxo), tauro-3α,7α-dihydroxy-5β-cholanoic
acid (TCDC), tauro-3α,6α,7α-trihydroxy-5β-cholanoic acid (THC), and tauro-3α,6α-dihydroxy-5β-cholanoic acid (THDC) were found
to contribute each for 4 to 5% ot the total. An excellent correlation was found between the sum of conjugated bile salts quantitated
by high-performance liquid chromatography (HPLC) and values obtained by conventional enzymatic assay. Simplicity, efficiency
and relative rapidity of the method render it suitable for routine analyses. 相似文献
9.
J. K. Weil F. D. Smith A. J. Stirton R. G. Bistline 《Journal of the American Oil Chemists' Society》1963,40(10):538-541
Even chain sodium alkanesulfonates from the Strecker reaction, odd chain sodium alkanesulfonates from the alkaline decarboxylation
of α-sulfo acids, and sodium 1-hydroxy-2-alkanesulfonates from the reduction of esters of α-sulfo acids were compared with
respect to Krafft point, critical micelle concentration, detergency and foam height. Sodium alkanesulfonates and crude fusion
products from the α-sulfo acids (mixtures of alkanesulfonates of one less carbon atom with a lesser amount of a soap of two
less carbon atoms) are more soluble and have better detergent and foaming properties. Sodium 1-hydroxy-2-alkanesulfonates
resemble monosodium salts of α-sulfo acids.
Alkanesulfonic acids and 1-hydroxy-2-alkane-sulfonic acids obtained from the sodium salts by ion exchange have lower Krafft
points and are more readily soluble. The critical micelle concentrations of 1-hydroxy-2-alkanesulfonic acids and α-sulfo acids
are nearly the same and about equal to those of alkanesulfonic acids of one less carbon atom.
Presented at the AOCS meeting in Toronto, Canada, 1962.
A laboratory of the E. Utiliz. Res. & Dev. Div., ARS, U.S.D.A. 相似文献
10.
Glycodihydrofusidate, which has the same detergent properties as bile salts, is excreted almost exclusively by the bile duct
after intravenous injection in the rat. As with bile salts, it leads to a significant (P≤0.05) increase in excretion of lecithins
and cholesterol (0.15 μmol lecithin and 0.026 μmol cholesterol per 1 μmol of glycodihydrofusidate excreted). In addition,
this drug simultaneously inhibits excretion of both endogenous bile salts and bile pigments. 相似文献
11.
J. L. Berna C. Bengoechea A. Moreno R. S. Rounds 《Journal of surfactants and detergents》2000,3(3):353-359
Sulfonic acids of linear alkylbenzene (LAB) are converted into the corresponding sodium salts to produce the most widely used
anionic surfactant worldwide, linear alkylbenzene sulfonate (LAS). Used in many industrial applications and consumer products,
the physical and mechanical properties of the sulfonates are strongly dependent on the LAB manufacturing process. Until recently,
commercial alkylation of benzene has employed aluminum chloride or hydrogen fluoride catalysts, but a new fixed-bed alkylation
process (DETAL) has been developed with improved 2-phenyl isomer selectivity and low tetralin concentration. In order to better
understand the rheology of LAS in aqueous media, a comprehensive comparative evaluation of sulfonic acids and sodium sulfonates
of the three LAB process derivatives has been done using dynamic mechanical rheometry, steady shear viscometry, and X-ray
diffraction for phase identification. LAB sulfonic acids are Newtonian fluids in the temperature range of 20–60°C. The neat
AlCl3, HF, and DETAL sulfonic acids are Newtonian fluids within the temperature range of 20–60°C. At 30 wt%, all three sulfonates
are Newtonian at 20–60°C, and the 40 wt% AlCl3 sodium sulfonate remains in the Newtonian regime within this temperature range. Lamellar liquid crystalline phases have been
identified for the sulfonates in the concentration range of 40–60 wt% in water at 20–60°C, and a hexagonal lattice phase also
has been identified for DETAL sodium alkylbenzene sulfonate at 40 wt%, 60°C. The presence of anisotropic phases results in
non-Newtonian pseudoplastic behavior with time-dependent viscosity functions. 相似文献
12.
A new group of anionic surfactants, namely sodium salts of secondary alkanesulfonamidoacetic acid, were synthesized using
n-alkanesulfonyl chlorides as starting materials. These surfactants, having the formula: R–SO2–NH–CH2–COONa, with R = C12, C14, C16 and C18, were obtained in a simple way with quantitative yields. Different chain lengths and positional isomers of this new type
of surfactants are expected to present differences in surface properties and foamability. The surface properties including
critical micelle concentrations and minimal surface tensions γmin were determined for each prepared surfactant using surface tension measurements with a Wilhelmy plate. Surface excess and
minimum area per molecule at the air–water interface were determined for different concentrations at 25 and 50 °C using the
Gibbs equation. The foaming power was also determined by the Bartsch method, and the results obtained were compared to those
of a commercial surfactant, the linear alkylbenzenesulfonate. The stability of the foam formed was also evaluated. As expected,
these surfactants exhibit good surface properties and show good foaming power. 相似文献
13.
Asstract The properties of diacylglycerol and monoacylglycerol kinase activities present in 90,000 x g pellet and 90,000 × g supernatant
fractions from rat brain were examined and compared. Of the properties examined, time course (linear for 10 min), enzyme concentration,
pH optimum (7.4–7.5), varying ATP (5 mM) and Mg2+ (10 mM) concentrations all showed similar optima for both activities. The optima for acylglycerol (5 mM for diacylglycerols;
3 mM for monoacylglycerols) and deoxycholate concentrations (0.1% for diacylglycerol kinase; 0.03% for monoacylglycerol kinase)
differed slightly. Examination of the subcellular distribution for these activities also showed a similar pattern. All fractions
showed significant activities, but the most was in the supernatant fraction. The similarities in properties and localization
of the 2 kinase activities suggest a single enzyme may function. On this assumption, an extensive study using mono- and diacylglycerols
of varying fatty acid composition gave the following results: (a) acylglycerols with the same fatty acid present showed increasing
activity in the order: 1-monoacylglycerol, 2-monoacylglycerol and 1,2-diacylglycerols; (b) when saturated fatty acids were
present the order of decreasing activity varied directly with increasing chain length for C10→C20; (c) when one or more unsaturated fatty acids were present good activities resulted, but no clear pattern emerged, although
acylglycerols with18∶1 and18∶3 fatty acids were more active than those with18∶2 and20∶4 fatty acids. These patterns do not support a role for this kinase in producing phosphatidic acids or lyso phosphatidic acids
of the correct composition to act as precursors for the de novo synthesis of the predominant 1-stearoyl, 2-arachidonoyl molecular
species of phosphatidylinositol. 相似文献
14.
Activated carbon (AC) has been shown to be effective in reducing serum cholesterol and triglycerides. The mechanism for this
action is proposed to be a result of the removal of bile salts in the gut. In this paper, the adsorption of cholate, glycocholate,
taurocholate, chenodeoxycholate and deoxycholate on AC is studied in vitro. The results indicate that AC has a high capacity
for bile salts, completely removing them from solutions of up to 5 mM and at a rate consistent with physiological activity.
Of the 2 types of AC tested, one was shown to exhibit greater capacity and selectivity over the other. A negligible effect
was seen with variation of pH through the range 7–9. Desorption occurs in the presence of bile salt-free buffer, but to a
minimal extent. Based on these data, the adsorption of bile salts by AC appears to be a likely mechanism for AC-induced reduction
of serum lipids. 相似文献
15.
Nitrogen compounds were extracted from defatted rapeseed meal with 0–0.1 N aqueous sodium hydroxide or hydrochloric acid.
Extractions were carried out for 30 min in water bath at 20, 40, 60, 80 or 100 C. Samples were centrifuged and concentrations
of nitrogen and pH were measured. The highest extractability of N-compounds (more than 80% of total N) was at pH 9.5–10 and
30–45 C. The lowest extractability (20–25% of total N) was at pH 6.5–8, and 80–100 C, the region of heat denaturation, and
at pH 3.8–4 at 20 C (35% of total N). 相似文献
16.
Cholesterol biosynthesis from acetate-2-14C by the livers of suckling rats, which is known to be relatively slow, was increased 2–3-fold within 24 hours after severing
the bile duct. Cholesterol synthesis by sham-operated litter mates showed no change under similar treatment. Mevalonate biosynthesis
from acetate-2-14C in vitro by recombined liver microsomal supernatant (105,000×g) fractions from suckling rats also was only 10% of that of
comparable recombined fractions from normal controls (young adult rats which were consuming colony diet). Activity was not
improved by combining either the microsomal or supernatant fraction from suckling rat livers with the complementary fraction
from normal adult livers. On the other hand, activity was restored to 100% when microsomes from livers of duct-served suckling
rats were combined with the supernatant fraction from normal controls. Likewise, recombined liver fractions prepared from
adult rats fed synthetic diets exhibited low activity for mevalonate biosynthesis. Activity was restored by bile duct cannulation,
but inhibited when cholic acid was infused into the cannulated animal. Therefore, surgical procedures which interrupt the
enterohepatic recirculation of bile components lead to a restoration of cholesterol biosynthesis and, at least in the adult
animal where cannulation studies are practicable, this effect can be reversed readily by bile acid infusion.
A slow rate of fecal excretion of14C-cholic acid was observed in suckling rats and rats fed synthetic diets, apparently reflecting an efficient enterohepatic
recirculation of bile salts. The data suggest that under these dietary conditions bile salt retention either directly or indirectly
influences hepatic synthesis of cholesterol.
Presented in part before Federation of American Societies for Experimental Biology, Fed. Proc.24, 1078, 1965 (abstract). and in part at the AOCS Meeting, Los Angeles, April 1966.
Journal Paper No.2835, Purdue University Agricultural Experiment Station. 相似文献
17.
Elizabeth M. Kirby Marra J. Evans-Vader M. Adele Brown 《Journal of the American Oil Chemists' Society》1965,42(5):437-446
The length of polymethylene chains is determined by counting the number of, or measuring the position of, methylene vibration
peaks in the 1070–710 cm−1 and/or the 1380–1170cm−1 regions of the IR spectrum of salts of fatty acids. Plotting this peak position against the phase relationship of the vibration
in adjacent methylenes gives a curve which is independent of the chain length. (Thephase relationship, Φ/π=k/(m+1); where φ is the phase difference in radians between adjacent methylenes in a chain;m is the number of methylenes in the chain;k=1,2,3,…m, withk=1 generally assigned to the in-phase vibration.) Separate curves are obtained for methylene wagging and for two arrays of
coupled twisting-rocking vibrations.
Coupled twisting-rocking vibrations give as many as one peak per methylene group in the 1070–710 cm−1 region with silver, sodium, potassium and barium salts of saturated acids. Lead salt peaks split. These peaks show the total
length of salts of both saturated andtrans-unsaturated acids, but only the length of the carboxylate segment in salts ofcis-unsaturated acids. (The carboxylate segment comprises the carbons from the carboxylate carbon to the first unsaturated carbon,
inclusive.)
Wagging vibrations in the 1380–1170 cm−1 region show the total chain length of saturated salts and the length of the carboxylate segment in unsaturated salts, bothcis andtrans. This region also has peaks for twisting-rocking vibrations, and they are most conspicuous in the spectra of silver and barium
salts.
Presented in part at the AOCS meeting in Toronto, Canada, 1962. 相似文献
18.
Andrzej Piasecki Bogdan Burczyk Piotr Ruchała 《Journal of surfactants and detergents》1998,1(1):29-35
The 2-n-alkyl-5-carboxy-5-methyl-1,3-dioxanes were obtained in good yield from the reaction of aliphatic aldehydes with 2,2-bis(hydroxymethyl)propionic
acid in dichloromethane solution, catalyzed by p-toluenesulfonic acid monohydrate. Nuclear magnetic resonance analysis indicated that they were pure cis-isomers with the axial configuration of the carboxylic group at the C-5 carbon atom of the 1,3-dioxane ring. The acids were
converted, with retention of the configuration, to their sodium salts by reaction with sodium methoxide or sodium hydroxide
in methanol. The physicochemical properties of the acids and sodium salts, as well as their surface properties at the aqueous
solution-air interface, were determined. Critical micelle concentration, surface excess concentration, surface area demand
per molecule of sodium salts at the monomolecular surface layer, and standard free energy of micellization were determined
based on surface tension measurements.
Part XXXIV in the series: Chemical Structure and Surface Activity. Part XXXIII: A. Piasecki, A. Sokolowski, B. Burczyk, R.
Gancarz, and U. Kotlewska, Synthesis, Surface Properties and Hydrolysis of Chemodegradable Anionic Surfactants: Diastereomerically
Pure cis- and trans-2,5-Disubstituted-1,3-dioxanes. J. Colloid Interface Sci. 192:74–82 (1997). 相似文献
19.
C. Bluestein W. Rosenblatt J. R. Clark A. Stefcik 《Journal of the American Oil Chemists' Society》1973,50(12):532-536
The preparation of amphoteric surfactants by the condensation of mixed N-alkylethylenediamines and unsaturated acid derivatives,
particularly acrylic acid esters, was studied. The reaction proceeded readily near 100 C either neat or with solvents. Saponification
of the ester products yielded salts which were water-soluble. The mono- and disodium salts of mixed N-alkyl (C11.5 av) ethylenediamine dipropionic and diisobutyric acid (crotonic acid derived) as 1% active in water were completely soluble
at all pH levels. The solutions demonstrated no perceptible isoelectric range on addition of 1–10% concentrations of sodium
chloride. Data on surface tension, solubility, calcium tolerance, foam, viscosity, color, and density are presented.
Presented at the AOCS Meeting, New Orleans, May 1973. 相似文献
20.
Xiujin Liang Zhaoping Zhong Baosheng Jin Xiaolin Chen Weiling Li Hongge Wei Houkun Guo 《Korean Journal of Chemical Engineering》2010,27(5):1483-1491
An experimental study of the SNCR process with urea as reducing agent and sodium salts as additive has been carried out, and
detailed analysis of the reaction mechanism has been given here. In the temperature range of 800–975 °C, NO concentration
decreases at first and then increases while the concentration of N2O increases at first and then decreases with the increasing of temperature, and the turning point is 900 °C. With increasing
of normalized stoichiometric ratio of reduction nitrogen to NO
x
(NSR), NO removal efficiency increases, while the concentration of N2O also increases, which decreases overall NO
x
removal efficiency. With sodium salts as additive, the concentration of N2O decreases with increasing of sodium salts addition at all temperatures, while the concentration of NO decreases at first
and then increases at low-temperature side of the temperature window and increases at high-temperature side with additional
increasing, whose changing extent is smaller than N2O. Since sodium salts as additive can remove N2O effectively and have no large influence on the removal of NO, the effect of sodium salts as additive is the combined effect
of the production of active radicals and the removal of HNCO produced by the decomposition of urea through neutralization
reactions, which is more important. To achieve the same effect under each condition, the needed addition of NaOH and CH3COONa is less than that of Na2CO3 counting as Na atom. For the decomposition of CH3COONa can produce CH3COO, its addition can promote the reduction of NO more obviously at the lower temperature than Na2CO3 or NaOH. Overall NO
x
removal efficiency at 900 ‡C with NSR=1.5 had been improved from about 30% to 70.45% through the addition of sodium salts.
Sodium salts as additive caused the flue gas to become alkaline gas, but it was not serious for sodium salts existing as NaNCO. 相似文献