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PubMed1987

Arachidonic acid transfer from diacyl-sn-glycero-3-phosphocholine to ether phospholipids in rat peripheral blood lymphocytes.

The main phospholipid fractions of rat peripheral blood lymphocytes consisted of 30.8% diacylglycerophosphocholine and 20.3% diacylglycerophosphoethanolamine; the proportion of the ether phospholipids were small especially of alkyl- and alkenyl-glycerophosphoethanolamine (3.3 and 6.6% respectively). Other classes of phospholipids included glycerophosphoserine (10.5%), glycerophosphoinositol (6.5%) and sphingomyelin (13.6%). The incorporation of labeled arachidonic acid in the glycerophospholipids showed a rapid uptake into diacyl and ether classes of phospholipids and into triglycerides. When labeled cells were reincubated without arachidonic acid the diacylglycerophosphocholine rapidly lost its radioactivity, but a concomitant increase was observed in alkylacylglycerophosphocholine and more especially in alkenylacylglycerophosphoethanolamine and a smaller increase in alkyl- and diacyl-glycerophosphoethanolamine. The radioactivity was fairly constant in glycerophosphoserine and in glycerophosphoinositol, but decreased slightly in triglycerides. The arachidonic acid transfer reaction was completed after 2-3 hours reincubation. When labeled cells were reincubated in the presence of sodium cholate, the loss of radioactivity in the diacylglycerophosphocholine fraction increased. The transfer of arachidonic acid to ether phospholipids was the same with or without sodium cholate, but the later enhanced arachidonic acid transfer to diacylglycerophosphoethanolamine.

Animals↗

PubMed1990

Comparison of the central and renal dopamine-1 receptor.

The dopamine D-1 receptor from striatal membranes was compared with the dopamine DA-1 receptor from renal proximal tubules. The dopamine-1 receptors were solubilized with 1% sodium cholate and phospholipids after pretreatment with the dopamine-1 agonist, SKF R-38393. The soluble receptors were reconstituted into phospholipid vesicles after removal of sodium cholate. The receptors were studied by radioligand binding using the dopamine-1 antagonist [125I]-SCH 23982. The reconstituted dopamine D-1 and DA-1 receptor densities were similar. However, the affinity of the solubilized D-1 receptor was 17-fold greater than the solubilized DA-1 receptor. The affinity of membrane bound D-1 receptor to the radioligand was also greater than that noted for membrane bound DA-1 receptor. The mechanism for this difference remains to be determined.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1979

7alpha-Dehydroxylation of cholic acid and chenodeoxycholic acid by Clostridium leptum.

The rate of 7alpha-dehydroxylation of primary bile acids was quantitatively measured radiochromatographically in anaerobically washed whole cell suspensions of Clostridium leptum. The pH optimum for the 7alpha-dehydroxylation of both cholic and chenodeoxycholic acid was 6.5-7.0. Substrate saturation curves were observed for the 7alpha-dehydroxylation of cholic and chenodeoxycholic acid. However, cholic acid whole cell K0.5 (0.37 micron) and V (0.20 mumol hr-1mg protein-1) values differed significantly from chenodeoxycholic acid whole cell K0.5 (0.18 micron) and V (0.50 mumol-1 hr-1 mg protein-1). 7alpha-Dehydroxylation activity was not detected using glycine and taurine-conjugated primary bile acids, ursodeoxycholic acid, cholic acid methyl ester, or hyocholic acid as substrates. Substrate competition experiments showed that cholic acid 7 alpha-dehydroxylation was reduced by increasing concentrations of chendeoxycholic acid; however, chenodeoxycholic acid 7alpha-dehydroxylation activity was unaffected by increasing concentrations of cholic acid. A 10-fold increase in cholic and 7alpha-dehydroxylation activity occurred during the transition from logarithmic to stationary phase growth whether cells were cultured in the presence or absence of sodium cholate. In the same culture, a similar increase in chenodeoxycholic acid 7alpha-dehydroxylation was detected only in cells cultured in the presence of sodium cholate. These results indicate the possible existence of two independent systems for 7alpha-dehydroxylation in C. Leptum.

Chenodeoxycholic Acid↗

PubMed1990

5'-Nucleotidase from bull seminal plasma. Biochemical and biophysical aspects.

In bull seminal plasma 5'-nucleotidase is present in heterogeneous forms. The heterogeneity is abolished by treatment of bull seminal plasma with the detergent sodium cholate. The purified enzyme, which is a glycoprotein, shows an apparent molecular mass of 160 kDa on gel filtration in the presence of 50 mmol sodium cholate and an apparent molecular mass of 72 kDa upon SDS/polyacrylamide-gel electrophoresis. The 5'-nucleotidase of bull seminal plasma is a metalloprotein containing 2 zinc ions per molecule of dimeric protein. The removal of the two zinc ions from the protein results in a completely inactive apoenzyme. The substitution of the endogenous zinc with Co(II) Cu(II) produces a holoenzyme which is slightly activated in the case of Co(II), whereas, in the case of Cu(II) only 65% of the initial activity is recovered. The enzyme has a covalently attached glycosyl-phosphatidylinositol moiety which can be removed by treatment with phosphatidylinositol-specific phospholipase C. ESR studies have indicated a radius of 35 A for the protein and that Cu(II) binds to the metal-free enzyme to a site in which sulphur donors can be excluded.

5'-Nucleotidase↗

PubMed1983

Efficiency of various bile salt preparations for stimulation of Clostridium difficile spore germination.

Taurocholate, desoxycholate, and cholate stimulated germination of Clostridium difficile spores in broth medium and enhanced recovery of C. difficile spores on a selective agar medium. Desoxycholate and some crude taurocholate preparations also inhibited multiplication of vegetative cells. At a concentration of 1.2 X 10(-2) M, sodium cholate inhibited multiplication of vegetative cells, but at concentrations of 1.2 X 10(-3) to 2.4 X 10(-3) M, it stimulated germination without inhibiting cell multiplication. Thus, pure sodium taurocholate and sodium cholate may effectively be incorporated in cefoxitin-cycloserine-fructose agar, whereas some crude preparations of sodium taurocholate decrease recovery on this medium.

Bile Acids and Salts↗

PubMed1983

Inhibition of carp liver mitochondrial monoamine oxidase by some commonly-used detergents.

The inhibitory effects of some detergents commonly used in biochemical research on carp liver mitochondrial monoamine oxidase were examined. Sodium dodecylsulfate, octyl-beta-D-glucopyranoside, sodium cholate and Triton X-100 at relatively low concentrations caused strong dose-dependent inhibition of the activity towards tyramine, but digitonin caused only weak inhibition. Sodium dodecylsulfate, octyl-beta-D-glucopyranoside and sodium cholate caused almost complete inhibition of activity in the concentration ranges tested. The extent of inhibition by Triton X-100 was greater after preincubation at 37 degrees C for 30 min than that without preincubation, but with or without preincubation, the inhibition was not substrate-selective and was not complete at a relatively high concentration (2%) of Triton X-100. Without preincubation, the mode of inhibition by Triton X-100 was competitive and reversible with respect to the oxidations of 5-HT, tyramine and PEA, but after preincubation (37 degrees C for 30 min), it became noncompetitive and irreversible, depending on the concentration of detergent used. These findings suggest that it had different actions on the enzyme depending on preincubation. Triton X-100 also slightly changed enzyme sensitivity towards clorgyline and deprenyl, regardless of the preincubation time or the substrate used. Some possible mechanisms of the inhibitory effect of Triton X-100 are discussed.

Animals↗

PubMed2000

Stability of SUV liposomes in the presence of cholate salts and pancreatic lipases: effect of lipid composition.

The effect of bile salts (sodium cholate and sodium taurocholate), and pancreatic lipases on the structural integrity of SUV liposomes of different lipid compositions was studied. Liposomal membrane integrity was judged by bile salt or pancreatin-induced release of vesicle encapsulated 5,6-carboxyfluorescein, and vesicle size distribution before and after incubations. Bile salt concentration was 10 mM, while a saturated solution of pancreatin (mixed with equal volume of liposomes) was utilized. Results agree with earlier studies, demonstrating the instability of liposomes composed of lipids with low transition temperatures (PC and DMPC) in presence of cholates. Addition of cholesterol (1:1 lipid:chol molar ratio) does not substantially increase the encapsulated molecule retention. Nevertheless, liposomes composed of lipids with high transition temperatures (DPPC, DSPC and SM), retain significantly higher amounts of encapsulated material, under all conditions studied. Furthermore, the vesicles formed by mixing cholesterol with these lipids will possibly be sufficiently stable in the gastrointestinal tract for long periods of time. Sizing results reveal that in most cases release of encapsulated molecules is mainly caused by their leakage through holes formed on the lipid bilayer. However, in stearylamine containing DPPC and DSPC vesicles, the cholate-induced drastic decrease in vesicle size suggests total liposome disruption as the possible mechanism of encapsulated material immediate release.

Animals↗

PubMed2003

Enhanced bioavailability of process-induced fast-dissolving ibuprofen cogranulated with beta-cyclodextrin.

The objectives of this study were to evaluate the bioavailability of cogranulated and oven-dried ibuprofen (IBU) and beta-cyclodextrin (betaCD), in comparison to a physical mixture, and to examine the effect of endogenous bile on the bioavailability of the drug. In vitro dissolution studies were performed using USP type 2 apparatus. The granules and physical mixture were administered perorally in a crossover fashion, to male Wistar bile duct-nonligated rats. The granules were also perorally administered to bile duct-ligated rats. Blood samples were taken at different time intervals and the plasma analyzed for IBU. Dissolution of granules was faster than the physical mixture due to faster IBU-betaCD complex formation in solution from the former than the latter. The in vivo study showed that C(max), AUC(0-8), and the absolute bioavailability for the granules (49.0 microg/mL, 57.0 h x microg/mL and 80.6%, respectively) were almost one and half times that of the physical mixture (32.2 microg/mL, 38.4 h x microg/mL and 53.1%, respectively). However, in bile duct-ligated rats, lower C(max) and AUC(0-8) (15.9 microg/mL and 14.4 h x microg/mL, respectively) were obtained for the granules. Phase solubility study of IBU in an aqueous betaCD solution in the presence of the bile salt (sodium cholate), showed an increase in the solubility of IBU. Moreover, the stability constant value for the IBU-betaCD complex was also found to decrease as the sodium cholate concentration increased. These results indicated that the enhancement in the bioavailability of IBU was due to faster in-solution complex formation, and micelllar solubilization by the bile salt.

Animals↗

PubMed2005

In vitro evaluation of betamethasone-loaded nanoparticles.

The aim of the present work was to investigate the preparation of nanoparticles as a potential drug carrier in the treatment of various inflammatory diseases. A nanoprecipitation method was used to entrap betamethasone in a poly[epsilon-caprolactone] matrix. Process parameters such as the initial drug load, the surfactants (polyvinyl alcohol, PVA; sodium cholate, SC), and their concentration in the aqueous phase were analyzed for their influences on particle properties. Particle size changed with increasing surfactant concentrations (PVA: 250 to 400 nm; sodium cholate: 330 to 150 nm) due to changes in interface stability and viscosity of the aqueous phase. The zeta potential was around neutrality with PVA and between -28 and -42 mV with SC. Betamethasone encapsulation rates of about 75% and 90% slightly increased with higher surfactant concentration. Drug release profiles exhibited an initial burst release with both surfactants, PVA (8-18%) or SC (25-35%) followed by a sustained release delivering 15% to 40% of the entrapped drug within 48 hours. The present nanoparticulate formulations exhibit promising properties of a colloidal drug carrier for betamethasone. Although SC seems to be advantageous due to its biocompatibility, in terms of sustained drug release pattern, the use of PVA is favorable.

Betamethasone↗

PubMed1985

In-vitro enhancement of cholesterol dissolution by commonly used drugs.

A rotating disc apparatus was used to study the dissolution of cholesterol in sodium cholate solutions and ox bile. Drugs with structures that render them capable of lowering interfacial resistance were tested and shown to increase cholesterol dissolution rates in both systems. In sodium cholate solutions, loperamide (3 X 10(-4)M) increased the rate of dissolution by over six times, and a similar effect was observed with amitriptyline (3 X 10(-3)M), diphenhydramine (3 X 10(-3)M), dicyclomine (3 X 10(-3)M) and propantheline (3 X 10(-3)M). These drugs are as effective as benzalkonium chloride at these concentrations. Amitriptyline, propantheline, dicyclomine and diphenhydramine also increased cholesterol dissolution rates into ox bile. If these drugs are excreted into human bile in sufficient quantities and in an active form they may be able to enhance the speed of cholesterol gallstone dissolution therapy.

Animals↗

PubMed2006

Stereoisomeric separation of flavanones and flavanone-7-O-glycosides by capillary electrophoresis and determination of interconversion barriers.

The stereoisomeric separation of several flavanones and flavanone-7-O-glycosides has been achieved with capillary electrophoresis by adding native cyclodextrins or cyclodextrin derivatives to the background electrolyte. As an alternative method, micellar electrokinetic chromatography with sodium cholate as a chiral surfactant has been used for the epimeric separation of two flavanone-7-O-glycosides. The effect of buffer systems containing mixtures of cyclodextrin with either sodium dodecyl sulfate or sodium cholate upon the chiral recognition of flavanones and flavanone-7-O-glycosides as well as the variation of the background electrolyte (concentration of buffer and surfactant, pH value, organic modifier), and its influence on the resolution factor Rs was investigated. Temperature- and pH-dependent enantiomerization or epimerization barriers of several flavanones (naringenin, homoeriodictyol) and flavanone-7-O-glycosides (naringin, neohesperidin, prunin, narirutin) in basic media (pH values of 9-11) have been observed. Interconversion profiles featuring characteristic plateau formation of the elution pattern were observed at high pH and evaluated with the simulation software ChromWin to determine rate constants k(T) and Eyring activation parameters, DeltaG#(T), DeltaH#, and DeltaS#.

Cyclodextrins↗

PubMed1980

[Demonstration and characterization of tumor-associated antigenic components from cell membranes of a UV-induced murine sarcoma using the MEM technic].

Purification of tumour-associated antigenic material from the ascites sarcoma cells was attempted by extraction with 3 M KCl and SDS-polyacrylamide gel electrophoresis (SDS-PAGE). The antigenic activity was assayed in the macrophage-electrophoretic-mobility (MEM) test. Extraction of whole tumour cells with 3 M KCl results in preparations with low antigenic activity which on SDS-PAGE show a very heterogenous composition of more than 20 protein bands. On comparison of the antigenic activity of different subcellular fractions obtained by differential centrifugation of the homogenate, the antigenic activity could be alloted to the cell membrane fraction. With this cell membrane fraction, three extraction media -- 3 M KCl, 2% Triton X-100, and 5% sodium cholate -- were tested for their ability to selectively extract the antigenic membrane proteins. The Triton X-100 treatment solubilized the greatest amount of membrane protein. Both Triton X-100 and sodium cholate, however, produced very heterogeneous protein extracts. In contrast, 3 M KCl selectively extracted three membrane components: a glycoprotein of high molecular weight and two low-molecular-weight carbohydrate-free proteins. Removal of the KCl in the presence of Triton X-100 precipitates the carbohydrate-free proteins, while the glycoprotein remains in solution. Testing the components of the KCl-extracts in the MEM-test after isolation by preparative SDS-PAGE revealed antigenic activity only with the glycoprotein component.

Animals↗

PubMed1990

[Affinity chromatography of thyroxine-binding proteins from human serum].

The affinity matrix prepared by the attachment of L-thyroxine (T4) to epichlorohydrine-activated Sepharose 4B biospecifically absorbs the T4-binding globulin (TBG), 25K and 80/27K proteins, immunoglobulin G (IgG) and albumin (HSA) from human normal and retroplacental sera. The absorbed protein patterns were shown to depend on the immobilized T4 concentration, pH, temperature and incubation time. The potent eluents desorbing 85-100% of the protein are 1 mM NaOH, 3 M NH4SCN, 10(-5) M T4 or 3 mM 8-anilinonaphthalene-1-sulfonic acid (ANS) for TBG; NaOH, NH4SCN, 3 mM MgCl2 or 12mM sodium cholate for 25K protein and HSA; NaOH, NH4SCN or MgCl2 for the 80/27K and 25K proteins and IgG. Moreover, T4 desorbs small amounts (6-8%) of the 80/27K and 25K proteins, while sodium cholate elutes about 6% of TBG. The eluted from T4-Sepharose 4B and further purified TBG, 25K and 80/27K proteins display different [125I]T4-binding activities within the pH range from 2 to 9 and differ by their resistance to thermal inactivation at 50-80 degrees C. Double radial immunodiffusion analysis with the use of antisera to TBG, 25K, 80/27K, HSA and IgG demonstrated that the proteins share no common antigenic determinants. It was concluded that the novel 25K and 80/27K proteins represent endogenous components of the human blood thyroid hormone-binding protein system rather than fragments or aggregates of the known T4-binding proteins.

Chromatography, Affinity↗

PubMed2004

Functional properties, lipoxygenase activity, and health aspects of Lupinus albus protein isolates.

To utilize lupin seeds for food and pharmaceutical applications, lupin seeds were pretreated to remove oil using hexane or carbon dioxide. Two types of lupin protein isolate were prepared. Both types of protein isolate showed good foaming activity, comparable to egg white. Protein isolate extracted under acid conditions showed higher foaming activity than protein isolate extracted at neutral pH. The lipoxygenase activity was much reduced in both of the protein isolates. The protein isolate extracted at neutral pH showed a stronger angiotensin converting enzyme inhibition than the protein isolate extracted under acidic pH. In contrast, the protein isolate extracted under acid conditions had a greater sodium cholate binding capacity, comparable to that of cholestyramine. Lupin samples showed less DPPH radical scavenging activity than deoiled soybean. The deoiling method did not affect the functional properties, lipoxygenase activity, angiotensin converting enzyme inhibition, sodium cholate binding, and radical scavenging activity.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1989

In vitro adsorption of bile salts by colestipol hydrochloride.

The acid-base titration of colestipol hydrochloride exhibits no sharp inflection points, indicating a weakly basic anion-exchange copolymer. The swelling of colestipol hydrochloride in water and the adsorption of cholate anion are inversely related to pH and are, therefore, related to the ionization state of the copolymer. The Langmuir adsorption parameters at pH 7.5 and 37 degrees C are similar for cholate, glycocholate, and taurocholate anions. Adsorption capacity was not related to particle size and exceeded the adsorptive capacity of the external surface by three orders of magnitude. Therefore, it is believed that the swelling of colestipol hydrochloride makes extensive internal surface area available for adsorption of bile salts. The rate of adsorption depends on the concentration of sodium cholate to which the colestipol hydrochloride is exposed. Adsorption was complete within 5 min when the concentration was below the adsorptive capacity. In contrast, adsorption at levels of sodium cholate at or above the adsorptive capacity was not complete within a 3-hr test period.

Adsorption↗

PubMed1999

Conformational and aggregational properties of the gene 9 minor coat protein of bacteriophage M13 in membrane-mimicking systems.

The membrane-bound state of the gene 9 minor coat protein of bacteriophage M13 was studied in various membrane-mimicking systems, including organic solvents, detergent micelles, and phospholipid bilayers. For this purpose we determined the conformational and aggregational properties of the chemically synthesized protein by CD, FTIR, and HPSEC. The protein appears to be in a monomeric or small oligomeric alpha-helical state in TFE but adopts a mixture of alpha-helical and random structure after subsequent incorporation into SDS or DOPG. When solubilized by sodium cholate, however, the protein undergoes a transition in time into large aggregates, which contain mainly beta-sheet conformation. The rate of this beta-polymerization process was decreased at lower temperature and higher concentrations of sodium cholate. This aggregation was reversed only upon addition of high concentrations of the strong detergent SDS. By reconstitution of the cholate-solubilized protein into DOPG, it was found that the state of the protein, whether initially alpha-helical monomeric/oligomeric or beta-sheet aggregate, did not change. On the basis of our results, we propose that the principal conformational state of membrane-bound gene 9 protein in vivo is alpha-helical.

Amino Acid Sequence↗

PubMed1986

Microsomal binding sites for antioestrogens in rat liver. Properties and detergent solubilization.

The properties of an antioestrogen binding site (AEBS), which has high affinity and specificity for nonsteroidal antioestrogens and structurally related compounds, have been studied in rat liver microsomes. When subcellular organelles were separated on Percoll density gradients the distribution of the AEBS paralleled that of NADPH-cytochrome c reductase, indicating that the AEBS is associated with the endoplasmic reticulum. Saturation analysis showed that [3H]tamoxifen was bound to a single class of saturable binding sites in liver microsomes with a KD of 0.9 +/- 0.1 nM at 0 degrees C. The equilibrium KD was not significantly different at 22 degrees C. The KD calculated from the association and dissociation rate constants for [3H]tamoxifen binding at 0 degrees C and 22 degrees C was compatible with the KD measured at equilibrium. Ligand specificity studies using tamoxifen analogues showed qualitatively similar structure-affinity relationships for the AEBS from both rat liver and the MCF 7 breast cancer cell line. In general structural modifications caused correspondingly greater changes in affinity for rat liver AEBS than for MCF 7 AEBS. The AEBS was solubilized from microsomal membranes with sodium cholate. This was the only detergent of nine tested that solubilized the site in high yield without loss of activity. Solubilization using cholate was more effective in the presence of 1 M-NaCl. In the solubilized state there was an apparent loss of [3H]tamoxifen binding activity which could be restored by dilution of the detergent. Gel filtration indicated an Mr of 440,000-490,000 for the AEBS-cholate complex. These studies demonstrate that rat liver contains high concentrations of a microsomal AEBS which has similar properties and specificity to the AEBS previously described in human breast cancer cells. This site can be solubilized by sodium cholate to supply material suitable for further purification.

Animals↗

PubMed1999

Identification, characterization, and partial purification of 4 alpha-carboxysterol-C3-dehydrogenase/ C4-decarboxylase from Zea mays.

A microsomal preparation from seedlings of Zea mays catalyzed the NAD+-dependent oxidative decarboxylation of several substrates, including 4alpha-carboxy-cholest-7-en-3beta-ol, synthesized according to a new procedure, giving the first in vitro evidence for this enzymatic activity in a higher plant. A GC assay has been developed to detect the Delta7-cholestenone produced and the kinetic parameters of the microsomal system have been established. 4alpha-Carboxysterol decarboxylation shows an exclusive requirement for an oxidized pyridine nucleotide, with NAD+ being more efficient than NADP+. The decarboxylation reaction is independent of molecular oxygen. 4alpha-Carboxysterol-C3-dehydrogenase/C4-decarboxylase (4alpha-CD) is a microsome-bound protein which can be efficiently solubilized by detergents, including Brij W-1 and sodium cholate. The Brij W-1-solubilized enzyme was partially purified 290-fold by a combination of DEAE anion-exchange chromatography, Cibacron blue 3GA-agarose dye chromatography, and gel permeation. The apparent molecular mass of 4alpha-CD in sodium cholate was estimated to be 45 kDa. These results support the contention that demethylation at C4 of plant sterols is composed of two separate processes: an oxygen- and NAD(P)H-dependent oxidation of the 4alpha-methyl group to produce the 4alpha-carboxysterol metabolite (S. Pascal et al., J. Biol. Chem. 268, 11639, 1993) followed by oxygen-independent dehydrogenation/decarboxylation to produce an obligatory 3-ketosteroid.

Carboxy-Lyases↗