The Experts below are selected from a list of 207 Experts worldwide ranked by ideXlab platform
Robert Scott Prosser - One of the best experts on this subject based on the ideXlab platform.
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site specific labeling of protein lysine residues and n terminal Amino Groups with indoles and indole derivatives
Bioconjugate Chemistry, 2015Co-Authors: Sacha Thierry Larda, Dmitry Pichugin, Robert Scott ProsserAbstract:Indoles and indole-derivatives can be used to site-specifically label proteins on lysine and N-terminal Amino Groups under mild, nondenaturing reaction conditions. Hen egg white lysozyme (HEWL) and α-lactalbumin were labeled with indole, fluoroindole, or fluoroindole-2-carboxylate via electrophilic aromatic substitutions to lysine side chain Ne- and N-terminal Amino imines, formed in situ in the presence of formaldehyde. The reaction is highly site-selective, easily controlled by temperature, and does not eliminate the native charge of the protein, unlike many other common lysine-specific labeling strategies. 19F NMR was used to monitor reaction progression, and in the case of HEWL, unique resonances for each labeled side chain could be resolved. We demonstrate that the indole tags are highly selective for primary Amino Groups. 19F NMR demonstrates that each lysine exhibits a different rate of conjugation to indoles making it possible to employ these tags as a means of probing surface topology by NMR or m...
Wolfgang E. S. Unger - One of the best experts on this subject based on the ideXlab platform.
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determination of accessible Amino Groups on surfaces by chemical derivatization with 3 5 bis trifluoromethyl phenyl isothiocyanate and xps nexafs analysis
Analytical and Bioanalytical Chemistry, 2010Co-Authors: Nora Graf, Thomas Gross, Andreas Lippitz, Falko Pippig, Andreas Hollander, Wolfgang E. S. UngerAbstract:The determination of Amino Groups on surfaces capable of binding biomolecules is important for the understanding and optimization of technologically relevant coupling processes. In this study, three different types of Amino-functionalized model surfaces, Amino thiolate on Au, Amino siloxane on Si, and polyethylene (PE) foils and films reacted with 1,2-diAminoethane (DAE) were derivatized with 3,5-bis(trifluoromethyl)phenyl isothiocyanate. Subsequently, these samples were analyzed by chemical derivatization X-ray photoelectron spectroscopy (CD-XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). The determination of Amino Groups by this analytical approach allows gaining insight into the availability of Groups on surfaces that can actually serve as attachment sites for biomolecules in technical applications. In the case of the Amino thiolate on Au, almost 90% of the expected Amino Groups were detected by CD-XPS. Investigation of the Amino siloxane films revealed lower yields for the derivatization reaction in the order of 30%. The lowered reaction yields are thought to be due to interactions between the Amino siloxane’s Amino and silanol Groups or the underlying substrate, making them inaccessible to the derivatization agent. The aminated PE samples are characterized by a complex surface chemistry and structure, and reaction yields of the derivatization reaction cannot be unequivocally derived. However, 1–3% of the total carbon atoms in the surface layer were found to be bound to Amino Groups accessible to the derivatization agent. It can be concluded that, depending on the detailed character of the investigated Amino-terminated surface, the amount of Amino Groups accessible to CD-XPS can be substantially lower than the total amount of Amino Groups present at the surface.
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Determination of accessible Amino Groups on surfaces by chemical derivatization with 3,5-bis(trifluoromethyl)phenyl isothiocyanate and XPS/NEXAFS analysis
Analytical and Bioanalytical Chemistry, 2009Co-Authors: Nora Graf, Thomas Gross, Andreas Lippitz, Falko Pippig, Andreas Hollander, Wolfgang E. S. UngerAbstract:The determination of Amino Groups on surfaces capable of binding biomolecules is important for the understanding and optimization of technologically relevant coupling processes. In this study, three different types of Amino-functionalized model surfaces, Amino thiolate on Au, Amino siloxane on Si, and polyethylene (PE) foils and films reacted with 1,2-diAminoethane (DAE) were derivatized with 3,5-bis(trifluoromethyl)phenyl isothiocyanate. Subsequently, these samples were analyzed by chemical derivatization X-ray photoelectron spectroscopy (CD-XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). The determination of Amino Groups by this analytical approach allows gaining insight into the availability of Groups on surfaces that can actually serve as attachment sites for biomolecules in technical applications. In the case of the Amino thiolate on Au, almost 90% of the expected Amino Groups were detected by CD-XPS. Investigation of the Amino siloxane films revealed lower yields for the derivatization reaction in the order of 30%. The lowered reaction yields are thought to be due to interactions between the Amino siloxane’s Amino and silanol Groups or the underlying substrate, making them inaccessible to the derivatization agent. The aminated PE samples are characterized by a complex surface chemistry and structure, and reaction yields of the derivatization reaction cannot be unequivocally derived. However, 1–3% of the total carbon atoms in the surface layer were found to be bound to Amino Groups accessible to the derivatization agent. It can be concluded that, depending on the detailed character of the investigated Amino-terminated surface, the amount of Amino Groups accessible to CD-XPS can be substantially lower than the total amount of Amino Groups present at the surface.
Sacha Thierry Larda - One of the best experts on this subject based on the ideXlab platform.
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site specific labeling of protein lysine residues and n terminal Amino Groups with indoles and indole derivatives
Bioconjugate Chemistry, 2015Co-Authors: Sacha Thierry Larda, Dmitry Pichugin, Robert Scott ProsserAbstract:Indoles and indole-derivatives can be used to site-specifically label proteins on lysine and N-terminal Amino Groups under mild, nondenaturing reaction conditions. Hen egg white lysozyme (HEWL) and α-lactalbumin were labeled with indole, fluoroindole, or fluoroindole-2-carboxylate via electrophilic aromatic substitutions to lysine side chain Ne- and N-terminal Amino imines, formed in situ in the presence of formaldehyde. The reaction is highly site-selective, easily controlled by temperature, and does not eliminate the native charge of the protein, unlike many other common lysine-specific labeling strategies. 19F NMR was used to monitor reaction progression, and in the case of HEWL, unique resonances for each labeled side chain could be resolved. We demonstrate that the indole tags are highly selective for primary Amino Groups. 19F NMR demonstrates that each lysine exhibits a different rate of conjugation to indoles making it possible to employ these tags as a means of probing surface topology by NMR or m...
Purnananda Guptasarma - One of the best experts on this subject based on the ideXlab platform.
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n terminal sequencing by mass spectrometry through specific fluorescamine labeling of α Amino Groups before tryptic digestion
Analytical Biochemistry, 2011Co-Authors: Neeraj Dhaunta, Uzma Fatima, Purnananda GuptasarmaAbstract:We present a single-step procedure for the specific mass labeling of unblocked protein N termini. We show that the dye fluorescamine, which is commonly assumed to require mildly alkaline conditions for undergoing a nonspecific reaction with α- and e-Amino Groups associated with Amino acids, in fact shows a specific reaction only with α-Amino Groups present at protein N termini when mildly acidic conditions are used. We use this finding to label, identify, and sequence the trypsinolysis-derived N-terminal peptide of lysozyme, using only mass spectrometry, to illustrate how this method could be used with other proteins.
Josep Cornella - One of the best experts on this subject based on the ideXlab platform.
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pyrylium salts selective reagents for the activation of primary Amino Groups in organic synthesis
Synthesis, 2020Co-Authors: Yue Pang, Daniel Moser, Josep CornellaAbstract:Primary Amino Groups represent an ubiquitous category of functionalities in synthetic building blocks, drugs, and natural products. Therefore, such functionalities offer themselves as perfect handles for late-stage functionalization, and the development of robust and efficient strategies to transform these Groups is highly desirable. Despite the extremely challenging activation of the C–N bond, the past few years have witnessed the rapid development of deaminative transformations using pyrylium salts as activating reagents. In most cases, the pyridinium salts formed were activated by single electron transfer, giving alkyl radicals which were used in a series of transformations via nickel and photoredox catalysis. This short review aims to give an overview to related properties of pyrylium salts, their historical significance, and summarize the recent progress in the field of deaminative transformations using these reagents. 1 Introduction 2 Pyrylium and Pyridinium Salts 2.1 Historical Context 2.2 Structure and Reactivity 2.3 Pyrylium Synthesis 2.4 Historical Context of the Reactivity of Pyridinium Salts 3 Recent Progress on Deaminative Transformations of Primary Amino Groups by Pyrylium Salts 3.1 Metal-Catalyzed Cross-Couplings 3.2 Photoredox Catalysis and Photoinduced Reactions for C–C Bond Constructions 3.3 Borylations 3.4 SNAr Functionalization of Aminoheterocycles 4 Conclusion
