The Experts below are selected from a list of 8280 Experts worldwide ranked by ideXlab platform
Noriyuki Ishii - One of the best experts on this subject based on the ideXlab platform.
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Investigation on Stability of Transporter Protein, Glucuronide Transporter from Escherichia coli
Journal of Membrane Biology, 2010Co-Authors: Noriyuki IshiiAbstract:The glucuronide transporter GusB, the product of the gusB gene from Escherichia coli , is responsible for detoxification of metabolites. In this study, we successfully expressed GusB homologously in E. coli and investigated its oligomeric state in n -dodecyl-β- d -maltoside (DDM) Detergent Solution. Evidence for a pentameric state with a Stokes radius of 57 ± 2 Å for the purified GusB protein in DDM Solution was obtained by analytical size-exclusion HPLC. The elution peak corresponding to pentameric GusB is commonly seen in elution profiles in the different buffer systems examined over a wide pH range. Hence, it is likely that GusB resides in the membrane as a pentamer. Stability studies with different incubation periods with the typical lipids, such as dimyristoylphosphatidylcholine, and total E. coli phospholipids, as the representatives of both phosphatidylcholine and phosphatidylethanolamine, show some clues to two-dimensional crystallization of GusB with lipids.
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Investigation on Stability of Transporter Protein, Glucuronide Transporter from Escherichia coli
Journal of Membrane Biology, 2010Co-Authors: Noriyuki IshiiAbstract:The glucuronide transporter GusB, the product of the gusB gene from Escherichia coli , is responsible for detoxification of metabolites. In this study, we successfully expressed GusB homologously in E. coli and investigated its oligomeric state in n -dodecyl-β- d -maltoside (DDM) Detergent Solution. Evidence for a pentameric state with a Stokes radius of 57 ± 2 Å for the purified GusB protein in DDM Solution was obtained by analytical size-exclusion HPLC. The elution peak corresponding to pentameric GusB is commonly seen in elution profiles in the different buffer systems examined over a wide pH range. Hence, it is likely that GusB resides in the membrane as a pentamer. Stability studies with different incubation periods with the typical lipids, such as dimyristoylphosphatidylcholine, and total E. coli phospholipids, as the representatives of both phosphatidylcholine and phosphatidylethanolamine, show some clues to two-dimensional crystallization of GusB with lipids.
Kirk G Scheckel - One of the best experts on this subject based on the ideXlab platform.
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the speciation of silver nanoparticles in antimicrobial fabric before and after exposure to a hypochlorite Detergent Solution
Journal of Environmental Quality, 2009Co-Authors: Christopher A Impellitteri, Thabet Tolaymat, Kirk G ScheckelAbstract:Because of their antibacterial properties, silver nanoparticles are often used in consumer products. To assess environmental and/or human health risks from these nanoparticles, there is a need to identify the chemical transformations that silver nanoparticles undergo in different environments. Thus an antimicrobial sock material containing Ag nanoparticles was examined by X-ray absorption spectroscopy to identify the speciation of Ag. The material was exposed to a hypochlorite/Detergent Solution and subjected to agitation. An elemental Ag nanopowder was also exposed to the hypochlorite/Detergent Solution or to a 1 mol L{sup -1} NaCl Solution. Results showed that the sock material nanoparticles consisted of elemental Ag. After exposure to the hypochlorite/Detergent Solution, a significant portion (more than 50%) of the sock nanoparticles were converted, in situ, to AgCl. Results from exposures to elemental Ag nanopowder suggest that an oxidation step is necessary for the elemental Ag nanoparticles to transform into AgCl as there was no evidence of AgCl formation in the presence of chloride alone. As a result, if Ag ions leach from consumer products, any chloride present may quickly scavenge the ions. In addition, the efficacy of Ag, as an antimicrobial agent in fabrics, may be limited, or even negated, after washing inmore » Solutions containing oxidizers as AgCl is much less reactive than Ag ion.« less
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The speciation of silver nanoparticles in antimicrobial fabric before and after exposure to a hypochlorite/Detergent Solution.
Journal of Environmental Quality, 2009Co-Authors: Christopher A Impellitteri, Thabet Tolaymat, Kirk G ScheckelAbstract:Because of their antibacterial properties, silver nanoparticles are often used in consumer products. To assess environmental and/or human health risks from these nanoparticles, there is a need to identify the chemical transformations that silver nanoparticles undergo in different environments. Thus an antimicrobial sock material containing Ag nanoparticles was examined by X-ray absorption spectroscopy to identify the speciation of Ag. The material was exposed to a hypochlorite/Detergent Solution and subjected to agitation. An elemental Ag nanopowder was also exposed to the hypochlorite/Detergent Solution or to a 1 mol L{sup -1} NaCl Solution. Results showed that the sock material nanoparticles consisted of elemental Ag. After exposure to the hypochlorite/Detergent Solution, a significant portion (more than 50%) of the sock nanoparticles were converted, in situ, to AgCl. Results from exposures to elemental Ag nanopowder suggest that an oxidation step is necessary for the elemental Ag nanoparticles to transform into AgCl as there was no evidence of AgCl formation in the presence of chloride alone. As a result, if Ag ions leach from consumer products, any chloride present may quickly scavenge the ions. In addition, the efficacy of Ag, as an antimicrobial agent in fabrics, may be limited, or even negated, after washing inmore » Solutions containing oxidizers as AgCl is much less reactive than Ag ion.« less
Christopher A Impellitteri - One of the best experts on this subject based on the ideXlab platform.
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the speciation of silver nanoparticles in antimicrobial fabric before and after exposure to a hypochlorite Detergent Solution
Journal of Environmental Quality, 2009Co-Authors: Christopher A Impellitteri, Thabet Tolaymat, Kirk G ScheckelAbstract:Because of their antibacterial properties, silver nanoparticles are often used in consumer products. To assess environmental and/or human health risks from these nanoparticles, there is a need to identify the chemical transformations that silver nanoparticles undergo in different environments. Thus an antimicrobial sock material containing Ag nanoparticles was examined by X-ray absorption spectroscopy to identify the speciation of Ag. The material was exposed to a hypochlorite/Detergent Solution and subjected to agitation. An elemental Ag nanopowder was also exposed to the hypochlorite/Detergent Solution or to a 1 mol L{sup -1} NaCl Solution. Results showed that the sock material nanoparticles consisted of elemental Ag. After exposure to the hypochlorite/Detergent Solution, a significant portion (more than 50%) of the sock nanoparticles were converted, in situ, to AgCl. Results from exposures to elemental Ag nanopowder suggest that an oxidation step is necessary for the elemental Ag nanoparticles to transform into AgCl as there was no evidence of AgCl formation in the presence of chloride alone. As a result, if Ag ions leach from consumer products, any chloride present may quickly scavenge the ions. In addition, the efficacy of Ag, as an antimicrobial agent in fabrics, may be limited, or even negated, after washing inmore » Solutions containing oxidizers as AgCl is much less reactive than Ag ion.« less
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The speciation of silver nanoparticles in antimicrobial fabric before and after exposure to a hypochlorite/Detergent Solution.
Journal of Environmental Quality, 2009Co-Authors: Christopher A Impellitteri, Thabet Tolaymat, Kirk G ScheckelAbstract:Because of their antibacterial properties, silver nanoparticles are often used in consumer products. To assess environmental and/or human health risks from these nanoparticles, there is a need to identify the chemical transformations that silver nanoparticles undergo in different environments. Thus an antimicrobial sock material containing Ag nanoparticles was examined by X-ray absorption spectroscopy to identify the speciation of Ag. The material was exposed to a hypochlorite/Detergent Solution and subjected to agitation. An elemental Ag nanopowder was also exposed to the hypochlorite/Detergent Solution or to a 1 mol L{sup -1} NaCl Solution. Results showed that the sock material nanoparticles consisted of elemental Ag. After exposure to the hypochlorite/Detergent Solution, a significant portion (more than 50%) of the sock nanoparticles were converted, in situ, to AgCl. Results from exposures to elemental Ag nanopowder suggest that an oxidation step is necessary for the elemental Ag nanoparticles to transform into AgCl as there was no evidence of AgCl formation in the presence of chloride alone. As a result, if Ag ions leach from consumer products, any chloride present may quickly scavenge the ions. In addition, the efficacy of Ag, as an antimicrobial agent in fabrics, may be limited, or even negated, after washing inmore » Solutions containing oxidizers as AgCl is much less reactive than Ag ion.« less
Georges Daufin - One of the best experts on this subject based on the ideXlab platform.
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the role of surface tension of re used caustic soda on the cleaning efficiency in dairy plants
International Dairy Journal, 2007Co-Authors: Nicolas Alvarez, Genevieve Gesanguiziou, Georges DaufinAbstract:Abstract During the cleaning in place with recycled cleaning Solutions, an increase of suspended solids (SS) and a decrease of the surface tension ( γ ) of caustic soda (NaOH) Solutions were observed for various types of dairy equipment. The decrease of γ was shown to result from the chemical reactions of the milk protein and fat with the cleaning Solutions. In this work, the respective roles of SS and γ on the cleaning efficiency, cleanliness and cleaning rate were determined. The cleaning test consisted of an ultrafiltration membrane fouled with skimmed milk and cleaned using four NaOH-based Solutions: newly prepared NaOH (high γ ), re-used NaOH (low γ ) with and without pre-clarification and a newly prepared commercial Detergent Solution. In the range of γ (28.7–74.0 mJ m −2 ) and SS (0.0–1.7 g kg −1 ) studied, the cleaning efficiency and the membrane hydraulic cleanliness were similar (0.91–0.94 and 0.69–0.71, respectively). However, it was found that Solutions with a low γ resulted in a much faster cleaning rate. The presence of SS was mainly detrimental to the cleaning rate. For an efficient cleaning rate, high pH and low γ were important. A re-used NaOH Solution with both low γ and SS was as fast as the commercial Detergent Solution at the same temperature (50 °C).
Dieter Schubert - One of the best experts on this subject based on the ideXlab platform.
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the state of association of the na translocating reduced nicotinamide adenine dinucleotide quinone oxidoreductase in Detergent Solution an ultracentrifugation study
Progress in colloid and polymer science, 2004Co-Authors: Christos Tziatzios, Dieter Schubert, Peter Schuck, Roy C D Lancaster, Robert B Gennis, Blanca BarqueraAbstract:Na + :reduced nicotinamide adenine dinucleotide:quinone reductase (Na + -NQR) is a redox-driven sodium pump found in some bacterial respiratory chains. The oligomeric state of Na + -NQR from Vibrio cholerae was studied by sedimentation velocity and sedimentation equilibrium experiments in the analytical ultracentrifuge. Sedimentation velocity analysis of the purified enzyme in Solutions of the nonionic Detergent n-dodecyl-β-D-maltoside (Dm) revealed the presence of a nearly homogeneous protein population. From its sedimentation and diffusion coefficient, and considering reasonable amounts of Dm bound by the enzyme, it is shown that the component corresponds to monomeric Na + -NQR. This result is corroborated by sedimentation equilibrium experiments, performed under conditions of density matching for the bound Detergent. No influence of NaCl on the sedimentation behaviour of Na + -NQR was detected. The amount of the protein-bound Detergent was found to be about 0.57 g Dm per gram of protein.
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studying membrane proteins in Detergent Solution by analytical ultracentrifugation different methods for density matching
Progress in colloid and polymer science, 1999Co-Authors: Gottfried Mayer, Bernd Ludwig, H W Muller, J A Van Den Broek, R H E Friesen, Dieter SchubertAbstract:Determining the complex size and the association behaviour of intrinsic membrane proteins by analytical ultracentrifugation is usually performed in aqueous Solutions containing nonionic, nondenaturing Detergents. In sedimentation equilibrium experiments, the contribution of the protein-bound Detergent to the quantities of interest, as well as the contribution of free Detergent micelles to the sedimentation profiles, can be eliminated by performing the measurements at a solvent density which equals that of the Detergent (“density matching”). In the past, density matching had been almost exclusively done by substituting H2O by appropriate H2O/ D2O mixtures. We have now applied sucrose or glycerol to blank out the contribution of either nonaethylene glycol lauryl ether (C12E9) or Triton X-100 (reduced form). In addition, we adjusted the density of a N,N-dimethyllaurylamine N-oxide/C12E9 mixture to that of the solvent. The model protein used in our study was cytochrome c oxidase from Paracoccus denitrificans. We found that all approaches described work well: the results obtained were virtually identical to those determined in H2O/D2O mixtures. The Detergent densities to be matched, however, were lowered by both sucrose and glycerol. Sucrose and glycerol are well known for their ability to stabilize protein conformation; thus, applying these reagents for density matching, instead of D2O, could be helpful in ultracentrifuge studies on more labile membrane proteins.
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associations between erythrocyte band 3 protein and aldolase in Detergent Solution determining their stoichiometry by analytical ultracentrifugation
FEBS Journal, 1996Co-Authors: Elfriede Huber, Gerhard Spatzkumbel, Hans G Baumert, Dieter SchubertAbstract:The cytoplasmic domain of band 3, the predominant polypeptide of the erythrocyte membrane, represents a binding site for certain glycolytic enzymes. We have studied the association between human band 3 protein and aldolase, in order to clarify the role of the different band 3 oligomers as ligand binding sites. The experiments were performed on mixtures of solubilized band 3 and aldolase in Solutions of a nonionic Detergent, nonaethyleneglycol lauryl ether. The main technique applied was sedimentation equilibrium analysis in an analytical ultracentrifuge. In addition, nonequilibrium centrifugation techniques were used. To facilitate the evaluations, the aldolase was labelled with a dye. The following results were obtained. (1) With unmodified band 3, aldolase is bound exclusively or at least predominantly to the band 3 tetramer (but not to monomers or dimers). (2) The band 3 tetramer can bind up to four aldolase tetramers. (3) The band 3 tetramer/aldolase complex is unstable on the time scale of the techniques used. (4) Stable band 3 dimers (stabilized either covalently or noncovalently) can also associate with aldolase and can bind up to two aldolase tetramers. The results described, together with those reported previously, point at a prominent role of the band 3 tetramer in ligand binding.