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Results for “selective extraction”

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At least 145 records · Page 8Linked to original sources
PubMed1993

Selective extraction of alkaline phosphatase and 5'-nucleotidase from milk fat globule membranes by a single phase n-butanol procedure.

A single phase extraction procedure employing 8% (v/v) n-butanol at room temperature extracted over 90% of alkaline phosphatase activity and over 60% of 5'-nucleotidase activity from bovine milk fat globule membranes (MFGM). For 5'-nucleotidase, higher n-butanol concentrations lead to loss of activity, while lower concentrations were ineffective in extracting the enzyme. When extractions were performed at 0 degrees C, similar yields were obtained for alkaline phosphatase extraction with 8% (v/v) n-butanol, but 5'-nucleotidase extraction required 10% (v/v) n-butanol for similar yields. However, 5'-nucleotidase was less susceptible to denaturation during extraction at 0 degrees C. The Km values and substrate specificities for both alkaline phosphatase and 5'-nucleotidase were unchanged by extraction with 8% (v/v) n-butanol. The 8% (v/v) n-butanol extraction procedure provides a 3-fold purification step, and an enzyme preparation suitable for further purification.

1-Butanol↗
PubMed2000

Selective extraction of antenna chlorophylls, carotenoids and quinones from photosystem I reaction center.

By the ether treatment of lyophilized PSI pigment-protein complexes, all the carotenoids and the secondary acceptor phylloquinone (A1), and more than 90% of the Chl were removed to yield the PSI complex with 9-11 molecules of Chl per reaction-center unit. The complexes retained the primary electron donor and acceptor (P700 and A0), in addition to three FeS clusters (F(X), F(A) and F(B)), and showed an activity of highly efficient electron transfer when phylloquinone was reconstituted. The methods for the preparation and the characterization of the ether-extracted PSI complexes are reviewed in this article. We also review the studies done with this PSI preparation on (1) the identification of the absorption and fluorescence spectra of P700, (2) the nano- and picosecond reaction of A0 and A1, (3) the energy-gap dependency of the reaction rate between A0 and the artificial quinones reconstituted at the A1 site, (4) the direct excitation of P700 followed by the ultra-fast electron transfer from P700 to A0, and (5) the de- and re-stabilization of the PSI structure by the removal and reconstitution, respectively, of antenna Chl in the presence of certain lipids.

Carotenoids↗
PubMed1985

Selective extraction of small and large molecules from the cerebrospinal fluid by Purkinje neurons.

Cerebellar Purkinje neurons accumulated propidium iodide, granular blue, and horseradish peroxidase conjugated to wheat germ agglutinin but not unconjugated horseradish peroxidase, bisbenzimide, or Evans blue when these compounds were infused into the lateral cerebral ventricles of awake, unrestrained rats. Accumulation of propidium iodide by Purkinje neurons of the vermis was associated with a reproducible behavioral abnormality characterized by truncal tremor, ataxia, and nystagmus. Both the accumulation of propidium iodide in Purkinje cells and the behavioral abnormality were prevented by prior intracerebroventricular administration of ouabain or colchicine, drugs that block neuronal transport processes. The ability of cerebellar Purkinje neurons to extract small and large molecules from the cerebrospinal fluid has important implications for their physiology and pathology.

Animals↗
PubMed1995

Polyethylene glycol-modified avidin: a novel agent for the selective extraction of biotinylated immune-complex in an aqueous two-phase system.

Chicken avidin was chemically modified with 2,4-bis[O-methoxypoly(ethylene glycol)]-6-chloro-s-triazine (activated PEG2) to form PEG-avidin. The PEG-avidin, in which 78% of the amino groups were modified, retained 49% of the active biotin-binding sites. The modified avidin was partitioned preferentially into the PEG-phase in an aqueous two-phase system (PEG/dextran). Using PEG-avidin, the immune-complex formed between biotinylated anti-mouse IgG and its antigen IgG (mouse) molecules, was successfully transferred into the PEG-phase in an aqueous two-phase system. This finding leads to the effective isolation of a specific antigen among various kinds of antigens by partitioning with a two-phase system using PEG-avidin.

Animals↗
PubMed2006

Insecticidal effects of various concentrations of selected extractions of Cestrum parqui on adult and immature Ceratitis capitata.

Aqueous extracts of Cestrum parqui L'Héritier (Solanaceae) were evaluated at different concentrations in several stages of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). For adults, the study was extended to extracts obtained with several solvents of an increasing degree of polarity. Aqueous extracts from C. parqui showed a high toxicity to neonate larvae when ingested through diet, inhibiting pupation at a concentration above 0.6%. Lower concentrations delayed the larval development and reduced the percentages of pupae formed and adult emergence. An LC50 = 0.9% after 3 d of continuous ingestion of C. parqui aqueous extracts could be calculated, whereas extracts obtained with organic compounds were nearly innocuous except with the use of the solvent methanol/water (80:20), the more polar of those tested, that killed 12.5% of adults. Aqueous extracts were also harmful to adults by diminishing the reproductive potential, which implies a significant effect on the offspring. Egg contact with insecticide or dipping third instars did not cause any adverse effect, supporting the hypothesis that only by means of ingestion can the toxic compounds of C. parqui reach the target. Our results showed that C. parqui components causing C. capitata mortality are mostly dissolved in water and not in organic solvents, which point out their polar character.

Animals↗
PubMed2001

Evaluation and comparison of two selective extraction procedures for heavy metal speciation in sediments.

Two sequential extraction procedures (the former proposed by the Standard, Measurements and Testing-SM&T-program of European Union and the latter derived from those of Tessier and Forstner with various modifications) have been compared, by analyzing a reference material (CRM 601) certified for the content of heavy metals in the three solutions resulting from the SM&T procedure. Scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) was used to evaluate the composition of the residues after various extractions. Reliable results, both in terms of precision and accuracy, were obtained for the first two steps of the SM&T scheme. As regards the third step, because it was modified during this work, a direct comparison of our results with those certified is not possible. SEM analysis confirmed that the scheme previously used in the laboratory was more aggressive compared to the SM&T procedure, which has also the advantage that the only CRM available for metal partitioning in sediments is certified using this method.

Journal Article↗
PubMed2006

Selective extraction of uranium from a mixture of metal or metal oxides by a tri-n-butylphosphate complex with HNO(3) and H(2)O in supercritical CO(2).

In order to study the decontamination nature of the reactive extraction of uranium in the presence of some metal chemicals using a single-phase mixture of HNO(3), H(2)O and tri-n-butylphosphate (TBP) in supercritical carbon dioxide (SC-CO(2)), we measured the decontamination factors (DFs) of Sr, Zr, Mo, Ru, Pd, Ce and Nd from their mixture with U. These elements were originally added to U(3)O(8) as SrO, ZrO(2), MoO(3), RuO(2), Pd, CeO(2) and Nd(2)O(3), and the extraction was performed at 18 MPa and 323 K with the single-phase mixture. The DFs for these elements were determined to be greater than 10(3) when the molecular ratio of U to TBP in the extracted complex was greater than 0.3. Dilution by SC-CO(2) effectively increased the DFs.

Journal Article↗
PubMed2002

Isolation of immunogenic outer membrane proteins from Mannheimia haemolytica serotype 1 by use of selective extraction and immunoaffinity chromatography.

OBJECTIVE: To use antibodies produced by calves in response to infection with Mannheimia haemolytica in immunoaffinity chromatography for the identification and subsequent isolation of the dominant immunogenic antigens from bacteria grown in iron-deficient media. SAMPLE POPULATION: Serum from 10 calves actively infected with M haemolytica. PROCEDURE: An outer membrane protein fraction was obtained from sonicated salt-extracted M haemolytica cells by extraction with N-lauroyl sarcosinate. The immunoglobulin fraction of serum from calves actively infected with M haemolytica was used to prepare an immunoaffinity column. The immunoaffinity column was used to isolate the dominant immunogenic proteins from the outer membrane protein fraction. The resultant immunogenic protein fraction was subjected to ELISA and immunoblot methods as well as carbohydrate quantification. Sequencing of the N-terminal was performed on the most prominent protein. RESULTS: 5 immunogenic proteins with molecular weights of 42, 30, 24, 20, and 15 kd were isolated. The immunogenic protein fraction was found to contain 51% carbohydrate. The immunoaffinity column capacity was 1 microg of immunogenic protein/mL of gel. The N-terminal sequence of the 42-kd protein was Tyr-Gln-Thr-Tyr-Gln-Ser-X-Leu-Gln, where X could not be identified. CONCLUSIONS AND CLINICAL RELEVANCE: lmmunogenic proteins were isolated by use of immunoaffinity chromatography. A substantial amount of carbohydrates was co-purified in the process. Additional experiments are needed to determine whether the carbohydrates would hinder or enhance development of vaccine preparations. This method could potentially allow a more rapid production of antigens for use in vaccines.

Amino Acid Sequence↗