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Query: UMLS:C0016382 (flushing)
 6,387 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new physically adsorbed capillary coating for capillary electrophoresis-mass spectrometry (CE-MS) of basic proteins is presented, which is easily obtained by flushing the capillary with a polymer aqueous solution for two min. This coating significantly reduces the electrostatic adsorption of a group of basic proteins (i.e., cytochrome c, lysozyme, and ribonuclease A) onto the capillary wall allowing their analysis by CE-MS. The coating protocol is compatible with electrospray inonization (ESI)-MS via the reproducible separation of the standard basic proteins (%RSD values (n = 5) < 1% for analysis time reproducibility and < 5% for peak heights, measured from the total ion electropherograms (TIEs) within the same day). The LODs determined using cytochrome c with total ion current and extracted ion current defection were 24.5 and 2.9 fmol, respectively. Using this new coating lysozymes from chicken and turkey egg white could be easily distinguished by CE-MS, demonstrating the usefulness of this method to differentiate animal species. Even after sterilization at 120 degrees C for 30 min, lysozyme could be detected, as well as in wines at concentrations much lower than the limit marked by the EC Commission Regulation. Adulteration of minced meat with 5% of egg-white could also be analysed by our CE-MS protocol.
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PMID:Capillary electrophoresis-mass spectrometry of basic proteins using a new physically adsorbed polymer coating. Some applications in food analysis. 1523 6

The usefulness of a noncovalent, positively charged capillary coating for the efficient analysis of intact basic proteins with CE was studied. Capillaries were coated by subsequent flushing with solutions of 10% w/v Polybrene (PB), 3% w/v dextran sulfate (DS), and again 10% w/v PB. Coating characterization studies showed that stable coatings could be produced which exhibited a pH-independent and highly reproducible EOF. The PB-DS-PB coating was evaluated with Tris phosphate BGEs of various pH using the four basic model proteins: alpha-chymotrypsinogen A, ribonuclease A, cytochrome c, and lysozyme. Typical migration time RSDs for the proteins were less than 0.85%, and apparent plate numbers were above 125,000 using a capillary length of 40 cm. The high separation efficiency allowed detection of several minor impurities in the model proteins. Using a BGE of medium pH, the CE system with triple-layer coating appeared to be useful for the repeatable profiling of recombinant humanized mouse monoclonal immunoglobulin G(1) showing a characteristic pattern of glycoforms. The CE system was also applied to the characterization of two llama antibodies, which were produced in Saccharomyces cerevisiae, revealing the presence of a side product in one of the antibodies. The high migration time stability allowed the reliable determination of antibody-antigen binding by monitoring migration time shifts. Finally, the feasibility of using the PB-DS-PB coated capillaries for CE with mass spectrometric detection was shown by the characterization of the impure llama antibody sample.
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PMID:Capillary electrophoresis of intact basic proteins using noncovalently triple-layer coated capillaries. 1955 16

Specular neutron reflectivity was used to study the time course and nature of the interaction of the positively charged, peripheral membrane protein cytochrome c with supported bilayers of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) containing the anionic lipid 1-palmitoyl-2-oleoyl-glycero-3-phosphatidylserine (POPS). The supported bilayers were prepared by deposition on silicon blocks of two monolayers of DOPC, the second of which contained either 10 or 20 mol % POPS at surface pressures of either 15 or 20 mN/m using a combination of Langmuir-Blodgett and Schaefer deposition techniques. Each supported bilayer was initially characterized by specular neutron reflectivity using subphases of 10 mM NaCl aqueous solutions. Regardless of POPS content and bilayer deposition pressure, the molecular architecture of the bilayers was similar. The addition of cytochrome c resulted in an almost immediate change in reflectivity, which was well modeled by assuming that an additional layer was present next to the outer leaflet of the bilayer. The thickness of this layer, which contained the volume fraction of approximately 15% protein, was approximately 30 A (consistent with the cross-section of a single cytochrome c molecule). The addition of cytochrome c to the subphase also resulted in a change in the structure of the phospholipid bilayer, suggesting some penetration of cytochrome c into the bilayer. Specular neutron reflectivity studies after careful washing with solvent showed that although most of the protein was washed off by flushing 10 mM NaCl D2O through the cell a small amount remained both within the bilayer and bound to the membrane surface.
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PMID:Specular neutron reflectivity studies of the interaction of cytochrome c with supported phosphatidylcholine bilayers doped with phosphatidylserine. 1971

A new simple and fast noncovalent coating method based on poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) copolymer was developed for CE. Merely 2 min flushing of the capillary with the poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) copolymer was required. The copolymer is adsorbed onto the fused-silica surface by hydrogen bonding and electrostatic interactions. EOF was almost totally suppressed over a wide pH range. The coating conditions (flushing time, copolymer concentration, and the concentration and pH of background electrolyte solution) and the stability of the coating were optimized, and the coated capillary was successfully applied to the fast separation of four basic proteins: lysozyme, cytochrome c, ribonuclease A, and alpha-chymotrypsinogen A. Separation efficiencies were high, ranging from 386 000 to 738 000 plates/m at 40 mM pH 4.0 acetate buffer being comparable to values obtained on classical covalent PVP-coated capillary. The RSD of migration times of basic proteins for 200 times successive runs were all below 1.0% (n=200, 3 days). A successful capillary performance was demonstrated also to the separation of low- and high-density lipoproteins at acidic pH.
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PMID:Noncovalent poly(1-vinylpyrrolidone)-based copolymer coating for the separation of basic proteins and lipoproteins by CE. 1988 86

Spermine-graft-dextran (Spe-g-Dex) copolymer was synthesized and used as a non-covalent coating for the separation of proteins and neurotransmitters by capillary electrophoresis. The coating was obtained via flushing the capillary with 1.0% Spe-g-Dex copolymer solution for 2min. Electroosmotic flow (EOF) was strongly suppressed, ranging from -1.60x10(-9) to 3.65x10(-9)m(2)V(-1)s(-1). Effect of experimental conditions, such as the copolymer concentration, the concentration and pH of the background electrolyte (BGE), on the Spe-g-Dex coating was investigated. Separation of lysozyme, cytochrome c, ribonuclease A and alpha-chymotrypsinogen yielded high separation efficiencies ranging from 141000 to 303000plates/m and recoveries from 85.4% to 98.3% at pH 4.0 (284.0mM sodium acetate-acetic acid buffer, I=50mM). Run-to-run repeatabilities and day-to-day, and capillary-to-capillary reproducibilities were all below 1.7%. In addition, Spe-g-Dex coating allowed the successful separation of five neurotransmitters, 5-hydroxytryptamine, dopamine, epinephrine, isoprenaline, dobuamine at pH 4.0 with high separation efficiencies of 290000-449000plates/m.
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PMID:Spermine-graft-dextran non-covalent copolymer as coating material in separation of basic proteins and neurotransmitters by capillary electrophoresis. 2059 36