SEARCH · PubMed Health

Results for “Sodium Cholate”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources

PubMed1990

Effects of bile salts on the adsorption of a hydrophobic mutagen to dietary fiber.

The effect of the bile salts, sodium cholate, deoxycholate, glycocholate and taurocholate, on the solubility in aqueous solution of the hydrophobic, environmental mutagen, 1,8-dinitropyrene (DNP), was examined. In the absence of bile salts, the DNP appeared to precipitate out of solution, whereas bile salts at a concentration of greater than or equal to 4 mM maintained the DNP in solution. In the presence of the model dietary fiber, alpha-cellulose, the DNP absorbed to this preferentially. Bile salts reduced this adsorption at low alpha-cellulose levels, but had little effect at high alpha-cellulose levels. The implication of these results is that bile salts have solubilising properties that could affect the distribution of hydrophobic molecules, including mutagens, in the digestive tract.

Adsorption↗

PubMed1984

Isolation and subunit composition of membrane inorganic pyrophosphatase from rat-liver mitochondria.

The activity of inorganic pyrophosphatase (pyrophosphate phosphohydrolase, EC 3.6.1.1) extracted from rat-liver mitochondria with sodium cholate is distributed between three enzyme forms (I-III) which originally reside in the matrix (I) or the inner membrane (II and III). The three forms of pyrophosphatase were separated by means of hydroxyapatite chromatography. The Mr values for enzymes I-III, were 60 000, 120 000 and 210 000, respectively. Membrane pyrophosphatase II, which predominates, was purified to homogeneity. Its molecule consists of two subunits with Mr of 28 000 and 35 000 giving different peptide maps upon BrCN cleavage and polyacrylamide gel electrophoresis. The results suggest that pyrophosphatase II may represent a catalytic part of the membrane pyrophosphatase of these mitochondria.

Animals↗

PubMed1984

Implication of a tyrosine residue in the unspecific bile salt binding site of human pancreatic carboxylic ester hydrolase.

Tyrosine residues of the human pancreatic carboxylic-ester hydrolase (EC 3.1.1.1) (also referred to as cholesterol-ester hydrolase, EC 3.1.1.13) were nitrated in the ortho-position by the use of tetranitromethane. The specificity of the reaction has been verified and the inhibition observed was shown to be unrelated to the weak polymerization of the protein. Among the 27 tyrosines present in the enzyme, seven or eight were nitrated but only one residue, with a pK of 8.3, seems to be responsible for the loss of activity. This decrease in enzyme activity appears only in assays which were performed in the presence of bile salts, suggesting that of the two bile salt binding sites postulated on the enzyme, only one, referred to the as the 'unspecific site' (Lombardo, D. and Guy, O. (1980) Biochim. Act 611, 147-155), was modified. This is in agreement with the similar loss of enzyme activity observed on emulsified and soluble substrate. The most important result is the difference observed in experiments of the protective effects of bile salts. The protection with sodium taurodeoxycholate is independent of its critical micellar concentration, showing that monomers protect this site, whereas the protection observed in experiments with sodium cholate appears only for supramicellar concentrations of bile salt. Since this latter bile salt promotes the dimerization of the enzyme, we can conclude that a premicellar bile salt binding site (protected by monomers) is transformed in a functional micellar binding site (protected by micelles). This conformational transformation seems to be consecutive to the dimerization, as has been recently proposed.

Bile Acids and Salts↗

PubMed1992

Purification and characterization of a low M(r) GTP-binding protein, c25KG, from human platelet membranes.

A low M(r) GTP-binding protein with a M(r) of 26,000 has been purified from a sodium cholate extract of human platelet membranes by using an antibody raised against a synthetic peptide of c25KG, which was previously purified from human platelet cytosol (Nagata, N., et al. (1989) J. Biol. Chem. 264, 17000-17005). The M(r) of membranous c25KG (m-c25KG) was slightly higher than that from cytosolic c25KG (M(r) 25,000) and calculated to be 26,000. It was suggested that m-c25KG contains an equimolar amount of GDP. The purified protein could bind approx. 1 mol of [35S]guanosine 5'-O-(thiotriphosphate)(GTP gamma S)/mol of protein, with a Kd value of 50 nM. [35S]GTP gamma S-binding to this protein was inhibited by GTP and GDP, but not by ATP and ADP, showing that the binding is specific for guanine. In the presence of 10 mM Mg2+, the dissociation of [8,5'-3H]GDP from the m-c25KG occurred with a rate of 0.01 min-1. The rate of release of Pi from [gamma-32P]GTP-bound m-c25KG was calculated to be 0.03 min-1. These results indicate that c25KG is also present in membrane fraction of human platelet which has very similar biochemical properties in those of the cytosolic type.

Antibody Specificity↗

PubMed1992

Association of alpha-phosphatidylinositol-specific phospholipase C with phospholipid vesicles.

The alpha isoform of phosphatidylinositol-specific phospholipase C (alpha-PI-PLC, Mr 62,000) was purified from bovine brain. Enzyme activity was dependent on calcium, sodium cholate and showed the anticipated specificity for the phosphatidylinositols. Calcium interaction with this protein, investigated by gel filtration chromatography, showed no detectable binding at calcium concentrations adequate to activate the enzyme. Association of alpha-PI-PLC with phospholipid vesicles was studied by light scattering, fluorescence energy transfer and gel-filtration chromatography. The enzyme readily associated with vesicles of high charge density, with vesicles of crude acidic phospholipids and with PIP2. Interaction was characterized by a rapid association followed by slower addition of more protein to the phospholipid. Complexes containing 20-30 percent protein (by weight) were readily obtained. Calcium had only a small effect on this interaction. The protein-phospholipid complexes appeared to bind less calcium than a similar amount of phospholipid alone. Thus, alpha-PI-PLC did not appear to be a calcium-binding protein in either its free or membrane-associated states. Although alpha-PI-PLC showed the highest propensity to bind to phospholipids, a number of other proteins also associated with phospholipids under the conditions used. Thus, whether or not the observed interaction of alpha-PI-PLC with membranes was specific and biologically important or whether it was a process common to many proteins, was not known. Knowledge of this interaction may enhance our understanding of possible mechanisms for protein-membrane interactions in general.

Animals↗

PubMed1993

Purification and properties of cytochrome P-450 (P-450lun) catalyzing steroid 11 beta-hydroxylation in Curvularia lunata.

Addition of 11-deoxycortisol to the culture medium of Curvularia lunata induced the increase of cytochrome P-450 content and steroid 11 beta-hydroxylase activity. The enzyme in cell-free extract produces cortisol from 11-deoxycortisol in the presence of NADPH and O2. The enzyme was partially stabilized by glycerol, 11-deoxycortisol, GSH and PMSF. The hydroxylation activity was strongly inhibited by carbon monooxide and sulfhydryl reagents. Cytochrome P-450 located on the microsomal fraction was solubilized with Triton X-100 and sodium cholate and purified to apparent homogeneity by column chromatography. The purified cytochrome P-450 (P-450lun) has a molecular mass of 60 kDa and exhibits the absorption maximum at 392 nm in the spectrum of oxidized form in the presence of 11-deoxycortisol. The reduced CO difference spectrum has a maximal peak at 448 nm. 11 beta-Hydroxylation of 11-deoxycortisol was reconstituted by cytochrome P-450lun, C. lunata NADPH-cytochrome P-450 reductase and DLPC in the presence of NADPH and O2 with a turnover number of 207 nmol/min per nmol of cytochrome P-450. The reductase and DLPC could be partially replaced with the enzyme purified from yeast or pig testis microsome and lipids purified from C. lunata, respectively. P-450lun catalyzes bifunctionally 11 beta- and 14 alpha-hydroxylations of 11-deoxycortisol. Deoxycorticosterone, progesterone, androstenedione and testosterone are hydroxylated in the similar manner.

Animals↗

PubMed1990

Activation of phospholipase C in rabbit brain membranes by carbachol in the presence of GTP gamma S; effects of biological detergents.

Rabbit brain cortical membranes incubated with carbachol in the presence of GTP gamma S show a marked increase in the degradation of exogenous phosphatidylinositol 4,5-bisphosphate. This activation of phospholipase C is dependent on the presence of deoxycholate and maximal at 0.8-1 mM deoxycholate. There is negligible activation by carbachol alone but in the presence of GTP gamma S a carbachol effect can be readily demonstrated. Optimal activation of phospholipase C by carbachol was seen at 10 to 100 nM free Ca2+. Washing cortical membranes with hypertonic buffer extracted 60% of the membrane protein yet the carbachol and GTP gamma S coupling remained intact. Incubation of the membranes with lysophosphatidylcholine, Nonidet P-40, sodium deoxycholate or digitonin at concentrations considerably less than those frequently used to solubilize membrane proteins abolished the carbachol response. Octyl glucoside and sodium cholate also uncoupled receptor regulation of phospholipase C but only at concentrations where solubilization of membrane proteins occurred. Prior exposure of membranes to carbachol did not prevent the uncoupling observed as a result of detergent treatment. Incubation of the membranes with carbachol and GTP gamma S did not appear to be accompanied by specific release of either active phospholipase C or inhibitors of phospholipase C activity.

Animals↗

PubMedDate not supplied

Isolation, purification, and characterization of calcitonin gene-related peptide receptor.

Intact calcitonin gene-related peptide (CGRP) receptors were solubilized from porcine neural membranes using sodium cholate: potassium buffer. The solubilized receptors were purified sequentially by hydrophobic interaction and ion-exchange chromatography followed by specific affinity chromatography. Using these procedures, we have isolated 2 nmol of highly purified active CGRP receptor to a homogeneity (5 x 10(8)-fold purification). The isolated receptors retained their specificity and the capacity to bind to 125I-CGRP, and showed no cross-reactivity with a number of other peptides, except with amylin having 46% amino acid sequence homology to h-CGRP. The solubilized receptors were adsorbed by WGA-agarose and concanavalin-A, suggesting a glycoprotein nature. SDS-PAGE, size-exclusion HPLC, and autoradiography confirmed that CGRP receptor is a monomeric membrane protein with M(r) 66 kDa.

Animals↗

PubMed1995

A multistep procedure for the chemical inactivation of human immunodeficiency virus for use as an experimental vaccine.

The kinetics of inactivation of four different strains of HIV-1 (RF, MN, SF2 and IIIB) by beta-propiolactone (BPL) and binary ethylenimine (BEI) were studied under various conditions. The conditions that would be required for the reduction of virus infectivity by at least 10(20) TCID50 ml-1 were estimated on the basis of the experimental rates of inactivation obtained. A multiple step procedure including treatment with 0.2% BPL, 0.05% sodium cholate, 10 mM BEI and 0.02% formaldehyde was designed to inactivate HIV-1 for use as an experimental vaccine. Complete inactivation of virus infectivity was confirmed by prolonged cell culture. The experimental vaccine preparation was analysed for the presence of HIV-1 proviral DNA utilizing the polymerase chain reaction. After treatment with both BPL and BEI proviral DNA was detected in one of four samples using primers encoding a 244 bp segment of the pol region of the viral genome. Proviral DNA could not be detected in any of the four samples using primers encoding segments of > 400 bp in the gag and reverse transcriptase region.

AIDS Vaccines↗

PubMed1992

Osmolytes improve the reconstitution of luteinizing hormone/human chorionic gonadotropin receptors into proteoliposomes.

Rat ovarian membrane luteinizing hormone/human chorionic gonadotropin (LH/hCG) receptor was reconstituted into proteoliposomes. The ability of sodium cholate to extract and reconstitute hCG binding activity was dependent on the protein/detergent ratio. Trypsinization of the LH/hCG receptor containing proteoliposomes indicated that approximately 57% of hCG binding sites were oriented extravesicularly. The presence of 20% glycerol or other osmolytes during reconstitution increased the accessibility of LH/hCG receptors but not the activity of adenylate cyclase in proteoliposomes. This beneficial effect was independent of any specific detergent or its presence during detergent solubilization of proteins. Dynamic properties of membranes were monitored by electron spin resonance of 16-, 12-, and 5-doxyl stearic acid. Reconstituted proteoliposomes contain less ordered membrane lipids than do native membranes. Addition of glycerol before reconstitution increased the order of lipid bilayer and shifted it to the physical state of the native membrane. These findings are consistent with the hypothesis that a rise in membrane ordering increases the accessibility of membrane-bound LH/hCG receptors.

Adenylyl Cyclases↗

PubMed1983

Autoradiographic differentiation of multiple benzodiazepine receptors by detergent solubilization and pharmacologic specificity.

We have used light microscopic autoradiography to localize differentially Type 1 and 2 benzodiazepine receptors using pharmacologic and detergent treatment techniques. The triazolopyridazine CL218872 has preferential affinity for Type 1 receptors from which it displaces [3H]flunitrazepam selectivity. In biochemical experiments [3H]flunitrazepam binding sites with pharmacologic properties of Type 2 receptors are preferentially solubilized from brain membranes by detergents. We have now treated rat brain slices either with CL218872 or 2% sodium cholate and evaluated the autoradiographic distribution of [3H]flunitrazepam-labeled receptors. Whether calculated from the drug or detergent treated preparations, the relative densities of apparent Type 1 and 2 receptors are the same. Thus differential sensitivity to determine solubilization distinguishes the same two populations of receptors as Type 1 and 2 specific drugs.

Animals↗

PubMed1984

Purification and isoelectric heterogeneity of chicken tyrosinase.

Tyrosinase (EC 1.14.18.1) was purified from regenerating chicken feathers. Most of the enzyme activity was in the insoluble fraction, which was solubilized with 0.5% sodium cholate. Solubilized tyrosinase showed multiple forms on isoelectric focusing. The isoelectric points had the following pI values: 5.06, 4.83, 4.68, 4.56, 4.44, 4.32, 4.24, 4.14, 4.06 and 3.97. This tyrosinase fraction was subjected to trypsin (EC 3.4.21.4) cleavage, Sephacryl S-200, hydroxylapatite and DEAE-cellulose chromatography. Purified enzymatically active tyrosinase also showed multiple forms. Their isoelectric points were: 4.23, 4.14, 4.06, 3.99 and 3.91. Each active form had almost the same molecular weight, estimated at 66 000. Staining for 1,2-diol groups of glycoproteins and neuraminidase (EC 3.2.1.18) treatment suggested that chicken tyrosinase is a glycoprotein. The enzyme showed both dopa(L-3,4-dihydroxylphenylalanine) oxidase activity and tyrosine hydroxylase activity.

Animals↗

PubMed1985

Antiestrogen binding sites in rat liver nuclei.

Isolated, intact rat liver nuclei have high-affinity (Kd = 10(-9) M) binding sites that are highly specific for nonsteroidal antiestrogens, especially for compounds of the triphenylethylene series. Nuclear [3H]tamoxifen binding capacity is thermolabile, being most stable at 4 degrees C and rapidly lost at 37 degrees C. More [3H]tamoxifen, however, is specifically bound at incubation temperatures of 25 degrees C and 37 degrees C than at 4 degrees C although prewarming nuclei has no effect, suggesting exchange of [3H]tamoxifen for an unidentified endogeneous ligand. Nuclear antiestrogen binding sites are destroyed by trypsin but not by deoxyribonuclease I or ribonuclease A. The nuclear antiestrogen binding protein is not solubilized by 0.6 M potassium chloride, 2 M sodium chloride, 0.6 M sodium thiocyanate, 3 M urea, 20 mM pyridoxal phosphate, 1% (w/v) digitonin or 2% (w/v) sodium cholate but is extractable by sonication, indicating that it is tightly bound within the nucleus. Rat liver nuclear matrix contains high-affinity (Kd = 10(-9) M) [3H]tamoxifen binding sites present in 5-fold higher concentrations (4.18 pmol/mg DNA) than in intact nuclei (0.78 +/- 0.10 (S.D.) pmol/mg DNA). Low-speed rat liver cytosol (20 000 X g, 30 min) contains high-capacity (955 +/- 405 (S.D.) fmol/mg protein), low-affinity (Kd = 10.9 +/- 4.5 (S.D.) nM) antiestrogen binding sites. In contrast, high-speed cytosol (100 000 X g, 60 min) contains low-capacity (46 +/- 15 (S.D.) fmol/mg protein), high-affinity (Kd = 0.61 +/- 0.20 (S.D.) nM) binding sites. Low-affinity cytosolic sites constitute more than 90% of total liver binding sites, high-affinity cytosolic sites 0.3%-3.2%, and nuclear sites less than 0.5% of total sites.

Animals↗

PubMed1985

Simultaneous purification of multiple forms of rat liver microsomal cytochrome P-450 by high-performance liquid chromatography.

14 microsomal cytochromes P-450 were purified from the liver of untreated and phenobarbital- or 3-methylcholanthrene-treated male rats. Following solubilization of microsomes with sodium cholate, poly(ethylene glycol) fractionation and aminohexyl-Sepharose 4B chromatography, cytochromes P-450 were purified by high-performance liquid chromatography (HPLC), using a preparative DEAE-anion-exchange column. The pass-through fraction was further purified by HPLC using a cation-exchange column. Other fractions eluted on preparative DEAE-HPLC were further applied onto an HPLC using a DEAE-column. Five kinds (P-450UT-2-6), four kinds (P-450PB-1,2,4 and 5) and five kinds (P-450MC-1-5) of cytochromes P-450 were purified from untreated rats or rats treated with phenobarbital or 3-methylcholanthrene, respectively. HPLC profiles of tryptic peptides of cytochromes P-450UT-2 and P-450MC-2 were identical and the other profiles obtained from seven purified cytochromes P-450 were distinct from each other. Amino-terminal sequences of eight forms of cytochrome P-450 (UT-2, UT-5, PB-1, PB-2, PB-4, PB-5, MC-1 and MC-5) were distinct except for cytochromes P-450PB-4 and P-450PB-5.

Amino Acid Sequence↗

PubMed1996

Adult-male-specific S-warfarin (11S-OH) and progesterone (20 beta-OH) keto-reductases in rat hepatic microsomes are not identical.

Adult-male-specific reductase activities in rat hepatic microsomes use NADPH to reduce S-warfarin and progesterone to their 11S-OH and 20 beta-OH products, respectively (Apanovitch et al. (1992) Biochem. Biophys. Res. Commun. 184, 338-346). When microsomes were treated with increasing concentrations of detergent, S-warfarin (11S-OH) reductase (SW(11S)R) activity was subject to monophasic activation by Triton X-100, monophasic inhibition by sodium cholate, and, activation followed by inhibition with either CHAPS or dodecyl-beta-D-maltoside. A non-dialyzable, heat-sensitive factor in rat and rabbit sera activates microsomal SW(11S)R activity six- to eight-fold. Similar detergent inhibitions but no detergent or serum activations were observed for progesterone (20 beta-OH) reductase (P(20 beta)R) activity. A significant amount of SW(11S)R activity was lost during purification regardless of whether the detergent used for solubilization was activating or inhibiting. Octyl-Sepharose, hydroxyapatite, DEAE-cellulose and carboxymethyl matrices were used to partially purify SW(11S)R. P(20 beta)R activity co-purified with SW(11S)R and the most purified fraction contained two major and several minor polypeptides. Partially purified SW(11S)R is activated by detergents, serum, and salt. These and previous results indicate that SW(11S)R and P(20 beta)R are not identical even though they are both adult male-specific, integral membrane proteins apparently having their active sites exposed on the cytoplasmic surface of the endoplasmic reticulum.

20-Hydroxysteroid Dehydrogenases↗

PubMed1977

Bilirubin metabolism in the spiny dogfish, Squalus acanthias, and the small skate, Raja erinacea.

1. The main bilirubin conjugate in bile of spiny dogfish (Squalus Acanthias) and small skate (Raja Erinacea) is bilirubin monoglucuronide. 2. Microsomal preparations from dogfish and small skate liver have similar bilirubin UDPglucuronyltransferase (UDPGT) activity and catalyze the conjugation of bilirubin with glucose from UDPglucose. 3. The activity of bilirubin glucosidation (UDPGT) was 0.5 times UDPG1T activity in dogfish and 0.15 times in skate liver microsomes. 4. Sodium cholate increased UDPGT and UDPG1T activities in dogfish and skate liver microsomal preparations only minimally, but the detergent markedly increased thermolability of UDPGT in skate liver microsomes.

Animals↗

PubMed1984

Studies on Tetrahymena microsomal electron transport systems: solubilization of microsomal electron transport enzymes involved in fatty acid desaturation.

Tetrahymena microsomes were solubilized with five different detergents and the effect on electron transport enzymes involved in fatty acid desaturation was studied. Cytochrome b560ms and NADPH-cytochrome c reductase were solubilized with a low concentration detergent (0.25%), in the order of sodium deoxycholate greater than Renex 690 greater than Triton X-100 greater than octylglucoside greater than sodium cholate, whereas all of these detergents at the high concentration (1%) could solubilize preferentially both enzymes (70-100%). Increasing the concentration of various detergents from 0.5 to 1.0% did not produce an incremental change in NADH-ferricyanide reductase solubilization. NADH-cytochrome c reductase system, which would be catalyzed by the cooperation action of NADH-ferricyanide and cytochrome b560ms, was relatively inactivated by all detergents. Compared to the other four detergents, octylglucoside has a much higher recovery of stearoyl-CoA desaturase activities in the supernatant. Our study suggests that octylglucoside may be more useful for the isolation in active form of cyanide-sensitive factor (CSF) from Tetrahymena microsomes.

Animals↗

PubMed1992

Characterization of a G-protein from the mandibular organ of the lobster Homarus americanus (Nephropidae, Decapoda).

1. GTP-binding activity was found in both calf brain and male lobster mandibular organ (MO). There was approximately two to three times as much binding in the calf brain. 2. The GTP-binding activity could be extracted from the calf brain with sodium cholate, but not from the MOs. 3. Using ADP-ribosylation catalyzed by pertussis toxin, GTP-binding was shown to be the result of the presence of G-protein. In the lobster MO the G-protein alpha subunit has a molecular weight of about 42 kDa and may be of the Go or Gi varieties.

Adenosine Diphosphate Ribose↗