The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Scott A. Mcluckey - One of the best experts on this subject based on the ideXlab platform.
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Enhanced Reactivity in Nucleophilic Acyl Substitution Ion/Ion Reactions Using Triazole-Ester Reagents
Journal of The American Society for Mass Spectrometry, 2017Co-Authors: Zhou Peng, Feifei Zhao, Scott A. McluckeyAbstract:The acyl substitution reactions between 1-hydroxy-7-aza-benzotriazole (HOAt)/1-hydroxy-benzotriazole (HOBt) ester Reagents and nucleophilic side chains on peptides have been demonstrated in the gas phase via ion/ion reactions. The HOAt/HOBt ester Reagents were synthesized in solution and ionized via negative nano-electrospray ionization. The anionic Reagents were then reacted with doubly protonated model peptides containing amines, guanidines, and imidazoles in the gas phase. The complexes formed in the reaction cell were further probed with ion trap collision induced dissociation (CID) yielding either a covalently modified analyte ion or a proton transfer product ion. The covalent reaction yield of HOAt/HOBt ester Reagents was demonstrated to be higher than the yield with N -hydroxysuccinimide (NHS) ester Reagents over a range of equivalent conditions. Density functional theory (DFT) calculations were performed with a primary amine model system for both triazole-ester and NHS-ester reactants, which indicated a lower transition state barrier for the former Reagent, consistent with experiments. The work herein demonstrates that the triazole-ester Reagents are more reactive, and therefore less selective, than the analogous NHS-ester Reagent. As a consequence, the triazole-ester Reagents are the first to show efficient reactivity with unprotonated histidine residues in the gas phase. For all nucleophilic sites and all Reagents, covalent reactions are favored under long time, low amplitude activation conditions. This work presents a novel class of Reagents capable of gas-phase conjugation to nucleophilic sites in analyte ions via ion/ion chemistry. Graphical Abstract ᅟ
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enhanced reactivity in nucleophilic acyl substitution ion ion reactions using triazole ester Reagents
Journal of the American Society for Mass Spectrometry, 2017Co-Authors: Zhou Peng, Feifei Zhao, Scott A. McluckeyAbstract:The acyl substitution reactions between 1-hydroxy-7-aza-benzotriazole (HOAt)/1-hydroxy-benzotriazole (HOBt) ester Reagents and nucleophilic side chains on peptides have been demonstrated in the gas phase via ion/ion reactions. The HOAt/HOBt ester Reagents were synthesized in solution and ionized via negative nano-electrospray ionization. The anionic Reagents were then reacted with doubly protonated model peptides containing amines, guanidines, and imidazoles in the gas phase. The complexes formed in the reaction cell were further probed with ion trap collision induced dissociation (CID) yielding either a covalently modified analyte ion or a proton transfer product ion. The covalent reaction yield of HOAt/HOBt ester Reagents was demonstrated to be higher than the yield with N-hydroxysuccinimide (NHS) ester Reagents over a range of equivalent conditions. Density functional theory (DFT) calculations were performed with a primary amine model system for both triazole-ester and NHS-ester reactants, which indicated a lower transition state barrier for the former Reagent, consistent with experiments. The work herein demonstrates that the triazole-ester Reagents are more reactive, and therefore less selective, than the analogous NHS-ester Reagent. As a consequence, the triazole-ester Reagents are the first to show efficient reactivity with unprotonated histidine residues in the gas phase. For all nucleophilic sites and all Reagents, covalent reactions are favored under long time, low amplitude activation conditions. This work presents a novel class of Reagents capable of gas-phase conjugation to nucleophilic sites in analyte ions via ion/ion chemistry.
Zhou Peng - One of the best experts on this subject based on the ideXlab platform.
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Enhanced Reactivity in Nucleophilic Acyl Substitution Ion/Ion Reactions Using Triazole-Ester Reagents
Journal of The American Society for Mass Spectrometry, 2017Co-Authors: Zhou Peng, Feifei Zhao, Scott A. McluckeyAbstract:The acyl substitution reactions between 1-hydroxy-7-aza-benzotriazole (HOAt)/1-hydroxy-benzotriazole (HOBt) ester Reagents and nucleophilic side chains on peptides have been demonstrated in the gas phase via ion/ion reactions. The HOAt/HOBt ester Reagents were synthesized in solution and ionized via negative nano-electrospray ionization. The anionic Reagents were then reacted with doubly protonated model peptides containing amines, guanidines, and imidazoles in the gas phase. The complexes formed in the reaction cell were further probed with ion trap collision induced dissociation (CID) yielding either a covalently modified analyte ion or a proton transfer product ion. The covalent reaction yield of HOAt/HOBt ester Reagents was demonstrated to be higher than the yield with N -hydroxysuccinimide (NHS) ester Reagents over a range of equivalent conditions. Density functional theory (DFT) calculations were performed with a primary amine model system for both triazole-ester and NHS-ester reactants, which indicated a lower transition state barrier for the former Reagent, consistent with experiments. The work herein demonstrates that the triazole-ester Reagents are more reactive, and therefore less selective, than the analogous NHS-ester Reagent. As a consequence, the triazole-ester Reagents are the first to show efficient reactivity with unprotonated histidine residues in the gas phase. For all nucleophilic sites and all Reagents, covalent reactions are favored under long time, low amplitude activation conditions. This work presents a novel class of Reagents capable of gas-phase conjugation to nucleophilic sites in analyte ions via ion/ion chemistry. Graphical Abstract ᅟ
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enhanced reactivity in nucleophilic acyl substitution ion ion reactions using triazole ester Reagents
Journal of the American Society for Mass Spectrometry, 2017Co-Authors: Zhou Peng, Feifei Zhao, Scott A. McluckeyAbstract:The acyl substitution reactions between 1-hydroxy-7-aza-benzotriazole (HOAt)/1-hydroxy-benzotriazole (HOBt) ester Reagents and nucleophilic side chains on peptides have been demonstrated in the gas phase via ion/ion reactions. The HOAt/HOBt ester Reagents were synthesized in solution and ionized via negative nano-electrospray ionization. The anionic Reagents were then reacted with doubly protonated model peptides containing amines, guanidines, and imidazoles in the gas phase. The complexes formed in the reaction cell were further probed with ion trap collision induced dissociation (CID) yielding either a covalently modified analyte ion or a proton transfer product ion. The covalent reaction yield of HOAt/HOBt ester Reagents was demonstrated to be higher than the yield with N-hydroxysuccinimide (NHS) ester Reagents over a range of equivalent conditions. Density functional theory (DFT) calculations were performed with a primary amine model system for both triazole-ester and NHS-ester reactants, which indicated a lower transition state barrier for the former Reagent, consistent with experiments. The work herein demonstrates that the triazole-ester Reagents are more reactive, and therefore less selective, than the analogous NHS-ester Reagent. As a consequence, the triazole-ester Reagents are the first to show efficient reactivity with unprotonated histidine residues in the gas phase. For all nucleophilic sites and all Reagents, covalent reactions are favored under long time, low amplitude activation conditions. This work presents a novel class of Reagents capable of gas-phase conjugation to nucleophilic sites in analyte ions via ion/ion chemistry.
Feifei Zhao - One of the best experts on this subject based on the ideXlab platform.
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Enhanced Reactivity in Nucleophilic Acyl Substitution Ion/Ion Reactions Using Triazole-Ester Reagents
Journal of The American Society for Mass Spectrometry, 2017Co-Authors: Zhou Peng, Feifei Zhao, Scott A. McluckeyAbstract:The acyl substitution reactions between 1-hydroxy-7-aza-benzotriazole (HOAt)/1-hydroxy-benzotriazole (HOBt) ester Reagents and nucleophilic side chains on peptides have been demonstrated in the gas phase via ion/ion reactions. The HOAt/HOBt ester Reagents were synthesized in solution and ionized via negative nano-electrospray ionization. The anionic Reagents were then reacted with doubly protonated model peptides containing amines, guanidines, and imidazoles in the gas phase. The complexes formed in the reaction cell were further probed with ion trap collision induced dissociation (CID) yielding either a covalently modified analyte ion or a proton transfer product ion. The covalent reaction yield of HOAt/HOBt ester Reagents was demonstrated to be higher than the yield with N -hydroxysuccinimide (NHS) ester Reagents over a range of equivalent conditions. Density functional theory (DFT) calculations were performed with a primary amine model system for both triazole-ester and NHS-ester reactants, which indicated a lower transition state barrier for the former Reagent, consistent with experiments. The work herein demonstrates that the triazole-ester Reagents are more reactive, and therefore less selective, than the analogous NHS-ester Reagent. As a consequence, the triazole-ester Reagents are the first to show efficient reactivity with unprotonated histidine residues in the gas phase. For all nucleophilic sites and all Reagents, covalent reactions are favored under long time, low amplitude activation conditions. This work presents a novel class of Reagents capable of gas-phase conjugation to nucleophilic sites in analyte ions via ion/ion chemistry. Graphical Abstract ᅟ
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enhanced reactivity in nucleophilic acyl substitution ion ion reactions using triazole ester Reagents
Journal of the American Society for Mass Spectrometry, 2017Co-Authors: Zhou Peng, Feifei Zhao, Scott A. McluckeyAbstract:The acyl substitution reactions between 1-hydroxy-7-aza-benzotriazole (HOAt)/1-hydroxy-benzotriazole (HOBt) ester Reagents and nucleophilic side chains on peptides have been demonstrated in the gas phase via ion/ion reactions. The HOAt/HOBt ester Reagents were synthesized in solution and ionized via negative nano-electrospray ionization. The anionic Reagents were then reacted with doubly protonated model peptides containing amines, guanidines, and imidazoles in the gas phase. The complexes formed in the reaction cell were further probed with ion trap collision induced dissociation (CID) yielding either a covalently modified analyte ion or a proton transfer product ion. The covalent reaction yield of HOAt/HOBt ester Reagents was demonstrated to be higher than the yield with N-hydroxysuccinimide (NHS) ester Reagents over a range of equivalent conditions. Density functional theory (DFT) calculations were performed with a primary amine model system for both triazole-ester and NHS-ester reactants, which indicated a lower transition state barrier for the former Reagent, consistent with experiments. The work herein demonstrates that the triazole-ester Reagents are more reactive, and therefore less selective, than the analogous NHS-ester Reagent. As a consequence, the triazole-ester Reagents are the first to show efficient reactivity with unprotonated histidine residues in the gas phase. For all nucleophilic sites and all Reagents, covalent reactions are favored under long time, low amplitude activation conditions. This work presents a novel class of Reagents capable of gas-phase conjugation to nucleophilic sites in analyte ions via ion/ion chemistry.
Andres W. Martinez - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Reagent Pencils for Deposition of Reagents onto Paper-Based Microfluidic Devices
Micromachines, 2017Co-Authors: Isabelle C. Noxon, Leah E. Cuellar, Amanda L. Thraen, Andres W. Martinez, Chad E. Immoos, Philip J. CostanzoAbstract:Reagent pencils allow for solvent-free deposition of Reagents onto paper-based microfluidic devices. The pencils are portable, easy to use, extend the shelf-life of Reagents, and offer a platform for customizing diagnostic devices at the point of care. In this work, Reagent pencils were characterized by measuring the wear resistance of pencil cores made from polyethylene glycols (PEGs) with different molecular weights and incorporating various concentrations of three different Reagents using a standard pin abrasion test, as well as by measuring the efficiency of Reagent delivery from the pencils to the test zones of paper-based microfluidic devices using absorption spectroscopy and digital image colorimetry. The molecular weight of the PEG, concentration of the Reagent, and the molecular weight of the Reagent were all found to have an inverse correlation with the wear of the pencil cores, but the amount of Reagent delivered to the test zone of a device correlated most strongly with the concentration of the Reagent in the pencil core. Up to 49% of the total Reagent deposited on a device with a pencil was released into the test zone, compared to 58% for Reagents deposited from a solution. The results suggest that Reagent pencils can be prepared for a variety of Reagents using PEGs with molecular weights in the range of 2000 to 6000 g/mol.
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Reagent pencils: a new technique for solvent-free deposition of Reagents onto paper-based microfluidic devices
Lab on a chip, 2015Co-Authors: Haydn T. Mitchell, Isabelle C. Noxon, Philip J. Costanzo, Chad E. Immoos, Cory A. Chaplan, Samantha J. Carlton, Cheyenne H. Liu, Kirsten A. Ganaja, Nathaniel W. Martinez, Andres W. MartinezAbstract:Custom-made pencils containing Reagents dispersed in a solid matrix were developed to enable rapid and solvent-free deposition of Reagents onto membrane-based fluidic devices. The technique is as simple as drawing with the Reagent pencils on a device. When aqueous samples are added to the device, the Reagents dissolve from the pencil matrix and become available to react with analytes in the sample. Colorimetric glucose assays conducted on devices prepared using Reagent pencils had comparable accuracy and precision to assays conducted on conventional devices prepared with Reagents deposited from solution. Most importantly, sensitive Reagents, such as enzymes, are stable in the pencils under ambient conditions, and no significant decrease in the activity of the enzyme horseradish peroxidase stored in a pencil was observed after 63 days. Reagent pencils offer a new option for preparing and customizing diagnostic tests at the point of care without the need for specialized equipment.
Cheng Yao - One of the best experts on this subject based on the ideXlab platform.
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Copper‐Catalyzed Trifluoromethylation of Organic Zinc Reagents with an Electrophilic Trifluoromethylating Reagent.
ChemInform, 2015Co-Authors: Chang-sheng Wang, Haoyang Wang, Cheng YaoAbstract:Various aryl-, vinyl-, and alkyl zinc Reagents are trifluoromethylated with Togni′s Reagent under mild reaction conditions.
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Copper-catalyzed trifluoromethylation of organic zinc Reagents with an electrophilic trifluoromethylating Reagent
RSC Advances, 2015Co-Authors: Chang-sheng Wang, Haoyang Wang, Cheng YaoAbstract:A copper-catalyzed trifluoromethylation of aryl, vinyl and alkyl zinc Reagents with Togni's Reagent was described. Mechanistic studies indicated that the aryl group is initially transferred from the zinc Reagent to hypervalent iodine to form a tri-substituted hypervalent iodine intermediate. Consequent reductive-elimination via a concerted bond-forming step and/or radical pathway from this intermediate generates the trifluoromethylated arenes.
