Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “selective extraction”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 73 records · Page 4Linked to original sources
PubMed1986

Selective extraction of the DM-20 brain proteolipid.

Brain DM-20 proteolipid was previously shown to be structurally different from the myelin major proteolipid (MMPL). In an attempt to set up a large-scale purification of DM-20, we studied extraction of brain proteolipids with mixtures of methylene chloride containing up to 80% methanol. The CH2Cl2-CH3OH (3:7, vol/vol) mixture is highly selective for the extraction of bovine brain DM-20 compared to MMPL. Purified DM-20 was obtained after chromatography of the extract on methylated Sephadex.

Animals↗
PubMed1999

Rapid determination of theophylline in serum by selective extraction using a heated molecularly imprinted polymer micro-column with differential pulsed elution.

Molecular imprinting of theophylline in poly(methacrylic acid ethylene dimethacrylate) form binding sites with complementary size, shape and chemical functionalities to theophylline. This molecularly imprinted polymer (MIP) can be packed into a micro-column for selective solid phase extraction (SPE) of theophylline from 20 microl of sample solution. Its chemical inertness and thermal stability allow the use of various organic solvents and elevated column temperatures for effective binding of theophylline. Non-specific adsorption of interfering drugs on the MIP surface is eliminated by an intermediate wash with 20 microl of acetonitrile, prior to quantitative desorption of the bound theophylline by 20 microl of methanol for in-line UV spectrophotometric determination. In this differential pulsed elution (DPE) technique, both the column temperature and solvent flow rate can be optimized to enhance selectivity. Application of this micro-analytical method, molecularly imprinted solid phase extraction DPE (MISPE-DPE), is demonstrated for accurate determination of theophylline in human blood serum. The method is validated over a linear range from 2 microg/ml to at least 20 microg/ml.

Acetonitriles↗
PubMed1968

Mitotic apparatus: the selective extraction of protein with mild acid.

The treatment of isolated mitotic apparatus with mild (pH 3) hydrochloric acid results in the extraction of less than 10 percent of its protein, accompanied by the selective morphological disappearance of the microtubules. The same extraction can be shown to dissolve outer doublet microtubules from sperm flagella. A protein with points of similarity to the flagellar microtubule protein is the major component of the extract from mitotic apparatus.

Animals↗
PubMed2001

Selective extraction of palladium(II) with theophylline derivatives.

Theophylline derivatives with some kinds of alkyl chains were synthesized and used in extraction experiments involving metal ions. Theophylline derivatives have exhibited a high selectivity for palladium over other precious metals and base metals. The extraction of palladium from acidic chloride media has been investigated using theophylline derivatives (= RN) as extractants. Palladium(II) was found to be extracted with 7-octyltheophylline according to the following reaction: PdCl2 + 2RN <==> PdCl2(RN)2. The extraction equilibrium constant was determined to be K = 2.67 x 10(8) ( moldm(-3))(-2). In addition, the stripping of palladium was performed to an extent of 100% by a single batchwise treatment with a 1.0 mol dm(-3) ammonia solution. The stoichiometric relation in the extraction of palladium was supported by an analysis using mass spectrometry.

Journal Article↗
PubMed1994

Selective extractability of noncollagenous proteins from chicken bone.

Quantitative analyses of a wide variety of different solvents used for the extraction of several of the noncollagenous proteins of fully mineralized chicken bone powder were carried out to compare both the effectiveness of various procedures and the distribution of specific proteins which were solubilized. Extraction procedures included solutions of 6 M guanidine-HCl, pH 7.0, 0.5 M EDTA, pH 7.4, 0.3 N citric acid, 0.3 N HCl, 0.3 N formic acid, and 0.3 N acetic acid. Chelation of calcium ions by EDTA and dissolution of the mineral phase by acid extraction released 95% or more of the total calcium content of the bone powder by 48 hours, guanidine-HCl released less than 20% or less of the total calcium content even when extraction was carried out by 168 hours. Moreover, although guanidine-HCl solubilized a significant amount of collagen as gelatin, essentially none of the phosphoproteins, osteocalcin, or the proteoglycan decorin were solubilized, as detected by immunological techniques. In contrast, extraction of the mineralized bone powder by HCl and formic acid was very efficient in selectively solubilizing osteocalcin and osteopontin, while bone sialoprotein was selectively released by EDTA, and solubilized to a lesser extent by formic acid. Similarly, EDTA selectively removed decorin compared with HCl, formic, acetic, or citric acids. Only small amounts of osteopontin and osteocalcin were detected in the acetic acid extracts. These results provide methods for the selective solubilization of several different major, noncollagenous proteins from mineralized bone which should significantly aid in maximizing the amount of the specific protein recovered, and the ease with which the various proteins can be purified.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Highly selective extraction of spiralin from the Spiroplasma citri cell membrane with alkyl-N-sulfobetaines.

The extraction of proteins from the membrane of the mollicute (mycoplasma) Spiroplasma citri by sodium N-dodecyl-N,N-dimethyl-3-amino-1-propane sulfonate (SB12) and sodium N-tetradecyl-N,N-dimethyl-3-amino-1-propane sulfonate (SB14) was studied with electrophoretic methods. The membranes were prepared by osmotic lysis of the cells and depleted of the bulk of extrinsic proteins. It was possible to extract up to 35 and 45% of membrane proteins with SB12 and SB14, respectively. Maximal yield was obtained in both cases with detergent concentrations greater than or equal to 5 mumoles/mg of membrane protein. Spiralin, the major protein in the S. citri membrane, was highly selectively solubilized without the loss of antigenicity, with a yield of about 90% with SB12 and close to 100% with SB14, for a detergent concentration greater than or equal to 0.2 M. The degree of selectivity in favour of spiralin was higher with SB12 (purity approximately equal to 70%) than with SB14 (purity approximately equal to 50%). Treatment of the S. citri membrane with high concentrations of SB12 is a simple and fast procedure for partial purification of spiralin. This example shows that, in some cases, it should be possible to modulate the selectivity of the extraction of membrane proteins simply by varying the relative concentration of detergent.

Bacterial Outer Membrane Proteins↗
PubMed2005

Selective extraction of derivates of p-hydroxy-benzoic acid from plant material by using a molecularly imprinted polymer.

Selective SPE of derivates of p-hydroxybenzoic acid (pHBA) from plant extract of Melissa officinalis is presented using a molecularly imprinted polymer (MIP) made with protocatechuic acid (PA) as template molecule. MIP was prepared with acrylamide as functional monomer, ethylene glycol dimethacrylate as crosslinking monomer and ACN as porogen. MIP was evaluated towards six phenolic acids: PA, gallic acid, pHBA, vanillic acid (VA), gentisic acid (GeA) and syringic acid (SyrA), and then steps of molecularly imprinted SPE (MISPE) procedure were optimized. The best specific binding capacity of MIP was obtained for PA in ACN (34.7 microg/g of MIP). Other tested acids were also bound on MIP if they were dissolved in this solvent. ACN was chosen as solvent for sample application. M. officinalis was extracted into methanol/water (4:1, v/v), the extract was then evaporated to dryness and dissolved in ACN before application on MIP. Water and ACN were used as washing solvents and elution of benzoic acids was performed by means of a mixture methanol/acetic acid (9:1, v/v). pHBA, GA, PA and VA were extracted with recoveries of 56.3-82.1% using this MISPE method. GeA was not determined in plant extract.

Acetic Acid↗
PubMed1976

Cytochemical evaluation of the Guard procedure a regressive staining method for demonstrating chromosomal basic proteins. I. Effects of fixation, blocking reactions, selective extractions, and polyacid "differentiation".

Appropriately fixed preparations stained by a modification of the Guard (1959) reaction for "sex chromatin" display selective staining of interphase chromatin and mitotic or meiotic chromosomes. This is a regressive staining method which seems to depend on the selective displacement of an acidic dye from less basic structures, and retention of the dye at more basic sites. The results obtained with the reaction can be controlled by the length of time that the preparations are "differentiated" in solutions containing phosphomolybdic and phosphotungstic acids (polyacids). After three- or four-hour exposures to polyacid solutions, all chromatin is stained. However, with longer differentiation, "condensed" chromatin can be stained preferentially. Of a number of fixatives investigated, only 10% formalin, ethanol-acetic acid (3:1), and Bouin's solution proved useful. Others resulted in diminished specificity or a total loss of selectivity. The most intense staining was obtained after formalin fixation. Less intense dyebinding was observed after fixation in 3:1 - probably due to extraction of some histone fractions-and the least amount of dye was bound in Bouin's-fixed chromatin - probably due to blockage of arginine residues by picric acid. The reaction was not affected by enzymatic removal of nucleic acids or the extraction of lipids. It was diminished by treatment with trypsin or weak acetylation, and it was completely prevented by strong acetylation, deamination, or extraction of basic proteins with HCl. The results presented suggest that the modified Guard (1959) procedure selectively demonstrates basic nucleoproteins. Further, by the use of regressive differentiation in polyacid solutions, the retention of dye in more condensed chromatin can be favored.

Animals↗
PubMed2005

Use of selective extraction and fast chromatographic separation combined with electrophoretic methods for mapping of membrane proteins.

A model system for selective solubilization and fast separation of proteins from the rat liver membrane fraction and purified rat liver plasma membranes for their further proteomic analysis is presented. For selective solubilization, high-pH solutions and a concentrated urea solution, combined with different detergents, are used. After extraction, proteins are separated by anion-exchange chromatography or a combination of anion- and cation-exchange chromatography with convective interaction monolithic supports. This separation method enables fast and effective prefractionation of membrane proteins based on their hydrophobicity and charge prior to one-dimensional (1-D) and 2-D electrophoresis and mass spectrometry. By use of this sample preparation method, the less-abundant proteins can be detected and identified.

Animals↗
PubMed2006

Temperature sensitive dopamine-imprinted (N,N-methylene-bis-acrylamide cross-linked) polymer and its potential application to the selective extraction of adrenergic drugs from urine.

A temperature sensitive dopamine-imprinted polymer was prepared in 80% aqueous methanol solution by free-radical cross-linking co-polymerisation of methacrylic acid and acrylamide at 60 degrees C in the presence of N,N-methylene-bis-acrylamide as the cross-linker and dopamine hydrochloride as template molecule. The resulting molecularly imprinted polymer (MIP) formed temperature responsive materials, which could be used for the selective separation of appropriate dopamine and adrenergic compounds from a liquid matrix at ambient temperatures. The thermoresponsive MIP exhibited a swelling-deswelling transition in 80% aqueous methanol solution at about 35 degrees C. The capacity of the thermoresponsive MIP to recognise the template molecule when present in aqueous methanol solution changed with temperature, with the highest selectivity found at 35 degrees C. Additionally, binding parameters obtained from Scatchard analyses indicate that increasing temperature resulted in an increased affinity and binding capacity of specific binding sites, but had less effect on non-selective binding sites. Subsequently, the thermoresponsive MIP was tested for its application as a sorbent material, utilisable in the selective solid-phase extraction (SPE) of dopamine and other adrenergic compounds (epinephrine, isoproterenol, salbutamol and serotonin) from urine samples. It was shown that the compounds that were structurally related to dopamine could be removed by elution, while dopamine and serotonin, the analytes of interest, remained strongly adsorbed to the adsorbent during SPE applications. The thermoresponsive MIP displayed different efficiency in clean-up and enrichments using the SPE protocol at different temperatures.

Acrylamides↗
PubMed2002

Solvent extraction selection in the determination of isoflavones in soy foods.

Acetonitrile is superior to acetone, ethanol and methanol in extracting the 12 phytoestrogenic soy isoflavone forms found in foods. At 53% organic solvent in water, raw soy flour, tofu, tempeh, textured vegetable protein and soy germ were evaluated for isoflavone extraction efficiency. The efficiency of acetonitrile extraction was demonstrated in mass balance evaluations of toasting of soy flour and soymilk heating.

Chromatography, High Pressure Liquid↗
PubMed2004

Selective extraction of acetic acid from the fermentation broth produced by Mannheimia succiniciproducens.

Acetic acid is by-product from fermentation processes for producing succinic acid using Mannheimia succiniciproducens . To obtain pure succinic acid from the final fermentation broth, acetic acid was selectively removed based on the different extractability of succinic acid and acetic acid with pH using tri-n-octylamine (TOA) as extractant. When successive batch extractions were performed using 0.25 mol TOA kg(-1) dissolved in 1-octanol at pH 5, the mol ratio of succinic acid to acetic acid before extraction was 4.9 and the final ratio after the fourth batch was 9.4.

Acetic Acid↗
PubMed2003

Selective extraction of persistent organic pollutants from environmental matrices.

An attempt is made to determine the bioavailability of persistent organic pollutants (POP's) in environmental matrices. The approach is based on the use of the Hildebrand Solubility Parameter, and its individual parameters of hydrogen bonding, dispersion and polarity to select weak and strong solvents to extract POP's from soil matrices. The approach has been applied to both spiked soils and certified reference materials. Initial results indicate that it is possible to fractionate POP's from soil matrices based on their ability to be extracted from soil by particular solvents.

Biological Availability↗
PubMed1979

Partial purification of the sugar carrier of intestinal brush border membranes. Enrichment of the phlorizin-binding component by selective extractions.

The [3H] phlorizin-binding component of brush border vesicles was enriched in situ by negative purification. Several procedures, known to effect selective solubilization of membrane components, were used separately or in combination to remove proteins unrelated to the binding. Deoxycholate ruptured the vesicles and released 67% of their protein, thereby increasing the specific [3H] phlorizin-binding activity of the pellet three-to fourfold. Extracting the deoxycholate-pellets with either NaI or alkaline solutions released up to 38% of the deoxycholate-insoluble protein without significantly affecting phlorizin binding. The polypeptide composition of the membranes at the different stages was analyzed by NaDodSO4-polyacrylamide gel electrophoresis. A number of polypeptides present in the original vesicles could be ruled out as essential components of the [3H] phlorizin binding entity. Intact and deoxycholate-treated vesicles were subjected to proteolytic attack. Papain liberated sucrase and isomaltase from intact vesicles, but affected neither other Coomassie-stained bands nor phlorizin binding. Neither the protein composition nor the binding properties of sealed vesicles were influenced by trypsin or chymotrypsin. However, all the proteolytic enzymes tested on deoxycholate-treated membranes substantially reduced [3H] phlorizin binding and produced concomitantly the disappearance of several bands from the electrophoretic profile. Pretreatment of vesicles with papain, followed by deoxycholate extraction and incubation in alkaline media, increased the specific binding activity of the membranes up to ninefold by removing close to 90% of the protein. A limited number of polypeptides are suggested as possible candidates for the glycoside-binding site of intestinal brush borders.

Animals↗
PubMed2006

A new calix[5]arene-based container: selective extraction of higher fullerenes.

[reaction: see text] A new double calix[5]arene successfully extracts higher fullerenes from fullerene mixtures. The syn isomer of the double calix[5]arene selectively captures higher fullerenes from fullerene mixtures. The elevation of the temperature more than 100 degrees C stimulates its conformational change to the anti isomer, bringing liberation of the captured higher fullerenes.

Journal Article↗
PubMed2005

A new molecularly imprinted polymer for selective extraction of cotinine from urine samples by solid-phase extraction.

Cotinine, the main metabolite of nicotine in human body, is widely used as a biomarker for assessment of direct or passive exposure to tobacco smoke. A method for molecularly imprinted solid-phase extraction (MISPE) of cotinine from human urine has been investigated. The molecularly imprinted polymer (MIP) with good selectivity and affinity for cotinine was synthesized using cotinine as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The imprinted polymer was evaluated for use as a SPE sorbent, in tests with aqueous standards, by comparing recovery data obtained using the imprinted form of the polymer and a non-imprinted form (NIP). Extraction from the aqueous solutions resulted in more than 80% recovery. A range of linearity for cotinine between 0.05 and 5 microg mL-1 was obtained by loading 1 mL blank urine samples spiked with cotinine at different concentrations in acetate buffer of pH 9.0, and by using double basic washing and acidic elution. The intra-day coefficient of variation (CV) was below 7% and inter-day CV was below 10%. This investigation has provided a reliable MISPE-HPLC method for determination of cotinine in human urine from both active smokers and passive smokers.

Chromatography, High Pressure Liquid↗
PubMed1990

Selective extraction of outer-membrane proteins from membrane complexes of Pseudomonas maltophila by chloroform-methanol.

An organic phase partitioning method is described for the selective purification of outer-membrane proteins (OMPs) from the total membrane complex of the opportunistic human and sheep pathogen, Pseudomonas maltophila. SDS-PAGE analysis confirmed that OMPs purified by chloroform-methanol treatment of the total membrane complex were not only identical to OMPs extracted from outer-membrane vesicles separated by sucrose gradient density centrifugation, but also possessed little or non-detectable levels of inner-membrane contaminants. Further analysis by enzyme linked immunosorbent assay (ELISA) and immunoblotting established that OMPs extracted by organic phase partitioning with chloroform-methanol retained antigenicity and serological activity indistinguishable from OMPs that were present in outer-membrane vesicles resolved by isopycnic sucrose density centrifugation of sarkosyl-treated membrane complexes.

Animals↗
PubMed1991

Selective extraction, solubilization, and reversed-phase high-performance liquid chromatography separation of the main proteins from myelin using tetrahydrofuran/water mixtures.

The number of solvents capable of dissolving myelin and proteolipid protein (PLP) and of being used as a mobile phase for the separation of myelin proteins by reversed-phase high-performance liquid chromatography (RP-HPLC) is very limited. In a thorough study, we found that aqueous tetrahydrofuran (THF) fulfilled such a requirement. The maximal amount of protein extracted corresponded to a THF/water ratio of 4:1 v/v and a polarity index of 5.16. This mixture dissolved a purified PLP preparation completely, 60% of proteins from fresh myelin, and 20% of white matter total proteins. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of those extracts, followed by densitometric analysis, showed that the amount and type of proteins dissolved depended on the polarity (i.e., the content of water) of the solvent mixture used. This selective effect was greater for basic protein in myelin preparations. Crude extracts highly enriched in basic protein can be prepared. In addition, the solvent system THF/water proved to be very useful as a mobile phase in RP-HPLC for separating myelin proteins. Using a C3 column and a linear gradient from 30% to 100% THF in water, both containing 0.1% trifluoroacetic acid (TFA), we separated completely the three main protein fractions of central nervous system (CNS) myelin in a short period of time. The high solubility power of THF/water mixtures prolonged greatly the life of the column.

Animals↗