The Experts below are selected from a list of 23433 Experts worldwide ranked by ideXlab platform
Xiaoqiang Qiao - One of the best experts on this subject based on the ideXlab platform.
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Imidazolium-embedded Iodoacetamide-functionalized silica-based stationary phase for hydrophilic interaction/reversed-phase mixed-mode chromatography.
Journal of separation science, 2016Co-Authors: Huizheng Wang, Lu Zhang, Liyuan Zhang, Xiaoqiang QiaoAbstract:A novel imidazolium-embedded Iodoacetamide-functionalized silica-based stationary phase has been prepared by surface radical chain-transfer polymerization. The stationary phase was characterized by Fourier transform infrared spectrometry, thermogravimetric analysis, and element analysis. Fast and efficient separations of polar analytes, such as nucleosides and nucleic acid bases, water-soluble vitamins and saponins, were well achieved in hydrophilic interaction chromatography mode. Additionally, a mixed mode of hydrophilic interaction and reversed-phase could be also obtained in the analysis of polar and nonpolar compounds, including weak acidic phenols, basic anilines and positional isomers, with high resolution and molecular-planarity selectivity, outperforming the commercially available amino column. Moreover, simultaneous separation of polar and nonpolar compounds was also achieved. In conclusion, the multimodal retention capabilities of the imidazolium-embedded Iodoacetamide-functionalized silica-based column could offer a wide range of retention behavior and flexible selectivity toward hydrophilic and hydrophobic compounds.
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imidazolium embedded Iodoacetamide functionalized silica based stationary phase for hydrophilic interaction reversed phase mixed mode chromatography
IEEE Journal of Solid-state Circuits, 2016Co-Authors: Huizheng Wang, Lu Zhang, Liyuan Zhang, Xiaoqiang QiaoAbstract:A novel imidazolium-embedded Iodoacetamide-functionalized silica-based stationary phase has been prepared by surface radical chain-transfer polymerization. The stationary phase was characterized by Fourier transform infrared spectrometry, thermogravimetric analysis, and element analysis. Fast and efficient separations of polar analytes, such as nucleosides and nucleic acid bases, water-soluble vitamins and saponins, were well achieved in hydrophilic interaction chromatography mode. Additionally, a mixed mode of hydrophilic interaction and reversed-phase could be also obtained in the analysis of polar and nonpolar compounds, including weak acidic phenols, basic anilines and positional isomers, with high resolution and molecular-planarity selectivity, outperforming the commercially available amino column. Moreover, simultaneous separation of polar and nonpolar compounds was also achieved. In conclusion, the multimodal retention capabilities of the imidazolium-embedded Iodoacetamide-functionalized silica-based column could offer a wide range of retention behavior and flexible selectivity toward hydrophilic and hydrophobic compounds.
Peter M. Shoolingin-jordan - One of the best experts on this subject based on the ideXlab platform.
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Inactivation of the polyketide synthase, 6-methylsalicylic acid synthase, by the specific modification of Cys-204 of the β-ketoacyl synthase by the fungal mycotoxin cerulenin
Biochemical Journal, 1998Co-Authors: J. Christopher Child, Peter M. Shoolingin-jordanAbstract:Cerulenin, [(2 S,3R)- 2,3-epoxy-4-oxo-7,10-dodecadienoylamide], a mycotoxin produced by Cephalosporium caerulens, irreversibly inactivated 6-methylsalicylic acid synthase from Penicillium patulum. A combination of radiolabelling studies with [ 3 H]cerulenin, proteolytic and chemical digestion and N-terminal sequencing of labelled peptides indicated that the site of cerulenin modification is the highly reactive substrate-binding Cys-204 of the β-ketoacyl synthase enzyme component. The thiol-specific inhibitor, Iodoacetamide, was also shown to alkylate this residue. These findings are analogous with those observed for the reaction of cerulenin and Iodoacetamide with type-I fatty acid synthases, demonstrating the close similarity between 6-methylsalicylic acid synthase and type-I fatty acid synthases.
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Inactivation of the polyketide synthase, 6-methylsalicylic acid synthase, by the specific modification of Cys-204 of the beta-ketoacyl synthase by the fungal mycotoxin cerulenin.
The Biochemical journal, 1998Co-Authors: C J Child, Peter M. Shoolingin-jordanAbstract:Cerulenin, [(2S,3R)-2,3-epoxy-4-oxo-7,10-dodecadienoylamide], a mycotoxin produced by Cephalosporium caerulens, irreversibly inactivated 6-methylsalicylic acid synthase from Penicillium patulum. A combination of radiolabelling studies with [3H]cerulenin, proteolytic and chemical digestion and N-terminal sequencing of labelled peptides indicated that the site of cerulenin modification is the highly reactive substrate-binding Cys-204 of the beta-ketoacyl synthase enzyme component. The thiol-specific inhibitor, Iodoacetamide, was also shown to alkylate this residue. These findings are analogous with those observed for the reaction of cerulenin and Iodoacetamide with type-I fatty acid synthases, demonstrating the close similarity between 6-methylsalicylic acid synthase and type-I fatty acid synthases.
Huizheng Wang - One of the best experts on this subject based on the ideXlab platform.
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Imidazolium-embedded Iodoacetamide-functionalized silica-based stationary phase for hydrophilic interaction/reversed-phase mixed-mode chromatography.
Journal of separation science, 2016Co-Authors: Huizheng Wang, Lu Zhang, Liyuan Zhang, Xiaoqiang QiaoAbstract:A novel imidazolium-embedded Iodoacetamide-functionalized silica-based stationary phase has been prepared by surface radical chain-transfer polymerization. The stationary phase was characterized by Fourier transform infrared spectrometry, thermogravimetric analysis, and element analysis. Fast and efficient separations of polar analytes, such as nucleosides and nucleic acid bases, water-soluble vitamins and saponins, were well achieved in hydrophilic interaction chromatography mode. Additionally, a mixed mode of hydrophilic interaction and reversed-phase could be also obtained in the analysis of polar and nonpolar compounds, including weak acidic phenols, basic anilines and positional isomers, with high resolution and molecular-planarity selectivity, outperforming the commercially available amino column. Moreover, simultaneous separation of polar and nonpolar compounds was also achieved. In conclusion, the multimodal retention capabilities of the imidazolium-embedded Iodoacetamide-functionalized silica-based column could offer a wide range of retention behavior and flexible selectivity toward hydrophilic and hydrophobic compounds.
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imidazolium embedded Iodoacetamide functionalized silica based stationary phase for hydrophilic interaction reversed phase mixed mode chromatography
IEEE Journal of Solid-state Circuits, 2016Co-Authors: Huizheng Wang, Lu Zhang, Liyuan Zhang, Xiaoqiang QiaoAbstract:A novel imidazolium-embedded Iodoacetamide-functionalized silica-based stationary phase has been prepared by surface radical chain-transfer polymerization. The stationary phase was characterized by Fourier transform infrared spectrometry, thermogravimetric analysis, and element analysis. Fast and efficient separations of polar analytes, such as nucleosides and nucleic acid bases, water-soluble vitamins and saponins, were well achieved in hydrophilic interaction chromatography mode. Additionally, a mixed mode of hydrophilic interaction and reversed-phase could be also obtained in the analysis of polar and nonpolar compounds, including weak acidic phenols, basic anilines and positional isomers, with high resolution and molecular-planarity selectivity, outperforming the commercially available amino column. Moreover, simultaneous separation of polar and nonpolar compounds was also achieved. In conclusion, the multimodal retention capabilities of the imidazolium-embedded Iodoacetamide-functionalized silica-based column could offer a wide range of retention behavior and flexible selectivity toward hydrophilic and hydrophobic compounds.
Paulette M. Vignais - One of the best experts on this subject based on the ideXlab platform.
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Inhibition by Iodoacetamide and Acetylene of the H‐D‐Exchange Reaction Catalyzed by Thiocapsa Roseopersicina Hydrogenase
European journal of biochemistry, 1996Co-Authors: Nikolay A. Zorin, Bernard Dimon, Jean Gagnon, Jacques Gaillard, Patrick Carrier, Paulette M. VignaisAbstract:The kinetics of H-D isotope exchange catalyzed by the thermostable hydrogenase from Thiocapsa roseopersicina have been studied by analysis of the exchange between D1 and H2O. The pH dependence of the exchange reaction was examined between pH 2.5 and pH 11. Over the whole pH range, HD was produced at a higher initial velocity than H2, with a marked optimum at pH 5.5; a second peak in the pH profile was observed at around pH 8.5. The rapid formation of H2 with respect to HD in the D2/H2O system is consistent with a heterolytic cleavage of D2, into D+ and an enzyme hydride that can both exchange with the solvent. The H-D-exchange activity was lower in the H2/D2O system than in the D2/H2O system. The other reactions catalyzed by the hydrogenase, H2 oxidation and H2 evolution, are pH dependent; the optimal pH were 9.5 for H2 uptake and 4.0 for H2 production. Treatment of the active form of hydrogenase by Iodoacetamide led to a slow and irreversible inhibition of the H-D exchange. When iodo[1-14C]acetamide was incubated with hydrogenase, the radioactive labeling of the large subunit was higher for the enzyme activated under H, than for the inactive oxidized form. Cysteine residues were identified as the alkylated derivative by amino acid analysis. Acetylene, which inhibits H-D exchange and abolishes the Ni-C EPR signal, protected the enzyme from irreversible inhibition by Iodoacetamide. These data indicate that Iodoacetamide can reach the active site of the H2-activated hydrogenase from T: roseopersicina. This was not found to be the case with the seleno hydrogenase from Desulfovibrio baculatus (now Desulfomicrobium baculatus). Cysteine modification by Iodoacetamide upon activation of the enzyme concomitant with loss of H-D exchange indicates that reductive activation makes at least one Cys residue of the active site available for alkylation.
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inhibition by Iodoacetamide and acetylene of the h d exchange reaction catalyzed by thiocapsa roseopersicina hydrogenase
FEBS Journal, 1996Co-Authors: Nikolay A. Zorin, Bernard Dimon, Jean Gagnon, Jacques Gaillard, Patrick Carrier, Paulette M. VignaisAbstract:The kinetics of H-D isotope exchange catalyzed by the thermostable hydrogenase from Thiocapsa roseopersicina have been studied by analysis of the exchange between D1 and H2O. The pH dependence of the exchange reaction was examined between pH 2.5 and pH 11. Over the whole pH range, HD was produced at a higher initial velocity than H2, with a marked optimum at pH 5.5; a second peak in the pH profile was observed at around pH 8.5. The rapid formation of H2 with respect to HD in the D2/H2O system is consistent with a heterolytic cleavage of D2, into D+ and an enzyme hydride that can both exchange with the solvent. The H-D-exchange activity was lower in the H2/D2O system than in the D2/H2O system. The other reactions catalyzed by the hydrogenase, H2 oxidation and H2 evolution, are pH dependent; the optimal pH were 9.5 for H2 uptake and 4.0 for H2 production. Treatment of the active form of hydrogenase by Iodoacetamide led to a slow and irreversible inhibition of the H-D exchange. When iodo[1-14C]acetamide was incubated with hydrogenase, the radioactive labeling of the large subunit was higher for the enzyme activated under H, than for the inactive oxidized form. Cysteine residues were identified as the alkylated derivative by amino acid analysis. Acetylene, which inhibits H-D exchange and abolishes the Ni-C EPR signal, protected the enzyme from irreversible inhibition by Iodoacetamide. These data indicate that Iodoacetamide can reach the active site of the H2-activated hydrogenase from T: roseopersicina. This was not found to be the case with the seleno hydrogenase from Desulfovibrio baculatus (now Desulfomicrobium baculatus). Cysteine modification by Iodoacetamide upon activation of the enzyme concomitant with loss of H-D exchange indicates that reductive activation makes at least one Cys residue of the active site available for alkylation.
Benilde Cosmi - One of the best experts on this subject based on the ideXlab platform.
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measurement of factor xiii fxiii activity by an automatic ammonia release assay using Iodoacetamide blank procedure no more overestimation in the low activity range and better detection of severe fxiii deficiencies
Clinical Chemistry and Laboratory Medicine, 2016Co-Authors: Michela Cini, Cristina Legnani, Mirella Frascaro, Claudia Pancani, Costanza Cappelli, G Rodorigo, Lelia Valdre, Benilde CosmiAbstract:BACKGROUND Laboratory investigation with specific factor XIII (FXIII) assays plays a crucial role in diagnosis of FXIII deficiency. According to the International Society on Thrombosis and Hemostasis (ISTH), it is necessary a blank sample with Iodoacetamide, provided by the kit or locally prepared, when the ammonia release assays are used, to avoid FXIII activity overestimation. METHODS In this study we set up a modification of the Berichrom FXIII chromogenic assay, in which Iodoacetamide was added by the BCS analyzer in the reaction mixture of the blank sample, without modifications of the original reagents. We analyzed 100 plasma samples of outpatients with clinical symptoms suggestive of a bleeding diathesis (20 samples had FXIII activity <20%). RESULTS In all samples blank subtraction significantly reduced FXIII activity, mostly in the low activity range group (from 10.1% to 2.4%, p<0.0001). In this group correction with Iodoacetamide also increased the agreement with the immunoassay and allowed FXIII activity measure up to 0%. CONCLUSIONS Despite the low number of samples included in the study, the described automatic procedure seemed to decrease FXIII activity overestimation and, especially for low activity range samples (<20%), to improve the agreement between FXIII activity and concentration. Our data suggested that Iodoacetamide correction could allow the detection of severe FXIII deficiencies (activity <5%) otherwise undiagnosed using the original method.
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Measurement of factor XIII (FXIII) activity by an automatic ammonia release assay using Iodoacetamide blank-procedure: no more overestimation in the low activity range and better detection of severe FXIII deficiencies
Clinical chemistry and laboratory medicine, 2016Co-Authors: Michela Cini, Cristina Legnani, Mirella Frascaro, Claudia Pancani, Costanza Cappelli, G Rodorigo, Lelia Valdre, Benilde CosmiAbstract:BACKGROUND Laboratory investigation with specific factor XIII (FXIII) assays plays a crucial role in diagnosis of FXIII deficiency. According to the International Society on Thrombosis and Hemostasis (ISTH), it is necessary a blank sample with Iodoacetamide, provided by the kit or locally prepared, when the ammonia release assays are used, to avoid FXIII activity overestimation. METHODS In this study we set up a modification of the Berichrom FXIII chromogenic assay, in which Iodoacetamide was added by the BCS analyzer in the reaction mixture of the blank sample, without modifications of the original reagents. We analyzed 100 plasma samples of outpatients with clinical symptoms suggestive of a bleeding diathesis (20 samples had FXIII activity
