scholarly journals A new charge-tagged proline-based organocatalyst for mechanistic studies using electrospray mass spectrometry

2014 ◽  
Vol 10 ◽  
pp. 2027-2037 ◽  
Author(s):  
J Alexander Willms ◽  
Rita Beel ◽  
Martin L Schmidt ◽  
Christian Mundt ◽  
Marianne Engeser
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Electrospray Mass Spectrometry ◽  
Temporal Evolution ◽  
Mechanistic Studies ◽  
Catalytic Center ◽  
Enamine Catalysis ◽  
Esi Mass Spectrometry ◽  
Catalyzed Reactions ◽  
Gas Phase Fragmentation

A new 4-hydroxy-L-proline derivative with a charged 1-ethylpyridinium-4-phenoxy substituent has been synthesized with the aim of facilitating mechanistic studies of proline-catalyzed reactions by ESI mass spectrometry. The charged residue ensures a strongly enhanced ESI response compared to neutral unmodified proline. The connection by a rigid linker fixes the position of the charge tag far away from the catalytic center in order to avoid unwanted interactions. The use of a charged catalyst leads to significantly enhanced ESI signal abundances for every catalyst-derived species which are the ones of highest interest present in a reacting solution. The new charged proline catalyst has been tested in the direct asymmetric inverse aldol reaction between aldehydes and diethyl ketomalonate. Two intermediates in accordance with the List–Houk mechanism for enamine catalysis have been detected and characterized by gas-phase fragmentation. In addition, their temporal evolution has been followed using a microreactor continuous-flow technique.

scholarly journals Compaction of RNA Hairpins and Their Kissing Complexes in Native Electrospray Mass Spectrometry

2020 ◽  
Author(s):  
Joséphine Abi-Ghanem ◽  
Clémence Rabin ◽  
Massimiliano Porrini ◽  
Frédéric Rosu ◽  
Valerie Gabelica
Keyword(s):  
Mass Spectrometry ◽  
Molecular Dynamics ◽  
Gas Phase ◽  
Electrospray Mass Spectrometry ◽  
Initial Structure ◽  
Native Solution ◽  
Phase Structures ◽  
Rna Hairpins ◽  
Level Calculation ◽  
Structure In Solution

When electrosprayed from native solution conditions, RNA hairpins and kissing complexes acquire charge states at which they get significantly more compact in the gas phase than their initial structure in solution. Here we show the limits of using force field molecular dynamics to interpret the gas-phase structures of nucleic acid complexes in the gas phase, and we suggest that higher-level calculation levels should be used in the future.<br>

scholarly journals Gas-Phase Fragmentation of Cyclic Oligosaccharides in Tandem Mass Spectrometry

Molecules ◽  
2019 ◽  
Vol 24 (12) ◽  
pp. 2226 ◽  
Author(s):  
Alexander O. Chizhov ◽  
Yury E. Tsvetkov ◽  
Nikolay E. Nifantiev
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Gas Phase ◽  
Structure Elucidation ◽  
Mass Spectra ◽  
Food Additives ◽  
Tandem Mass ◽  
Modern Mass ◽  
Gas Phase Fragmentation ◽  
Different Sources

Modern mass spectrometry, including electrospray and MALDI, is applied for analysis and structure elucidation of carbohydrates. Cyclic oligosaccharides isolated from different sources (bacteria and plants) have been known for decades and some of them (cyclodextrins and their derivatives) are widely used in drug design, as food additives, in the construction of nanomaterials, etc. The peculiarities of the first- and second-order mass spectra of cyclic oligosaccharides (natural, synthetic and their derivatives and modifications: cyclodextrins, cycloglucans, cyclofructans, cyclooligoglucosamines, etc.) are discussed in this minireview.

scholarly journals Mass Spectrometric Analysis of Antibody—Epitope Peptide Complex Dissociation: Theoretical Concept and Practical Procedure of Binding Strength Characterization

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4776
Author(s):  
Bright D. Danquah ◽  
Kwabena F. M. Opuni ◽  
Claudia Roewer ◽  
Cornelia Koy ◽  
Michael O. Glocker
Keyword(s):  
Mass Spectrometry ◽  
Dissociation Constant ◽  
Gas Phase ◽  
Immune Complex ◽  
Room Temperature ◽  
Electrospray Mass Spectrometry ◽  
Small Sample ◽  
Epitope Peptide ◽  
Ligand Complex ◽  
Dissociation Constant Kd

Electrospray mass spectrometry is applied to determine apparent binding energies and quasi equilibrium dissociation constants of immune complex dissociation reactions in the gas phase. Myoglobin, a natural protein-ligand complex, has been used to develop the procedure which starts from determining mean charge states and normalized and averaged ion intensities. The apparent dissociation constant KD m0g#= 3.60 × 10−12 for the gas phase heme dissociation process was calculated from the mass spectrometry data and by subsequent extrapolation to room temperature to mimic collision conditions for neutral and resting myoglobin. Similarly, for RNAse S dissociation at room temperature a KD m0g#= 4.03 × 10−12 was determined. The protocol was tested with two immune complexes consisting of epitope peptides and monoclonal antibodies. For the epitope peptide dissociation reaction of the FLAG peptide from the antiFLAG antibody complex an apparent gas phase dissociation constant KD m0g#= 4.04 × 10−12 was calculated. Likewise, an apparent KD m0g#= 4.58 × 10−12 was calculated for the troponin I epitope peptide—antiTroponin I antibody immune complex dissociation. Electrospray mass spectrometry is a rapid method, which requires small sample amounts for either identification of protein-bound ligands or for determination of the apparent gas phase protein-ligand complex binding strengths.

Study on the Gas Phase Stability of Heme-binding Pocket in Cytochrome Tb5 and Its Mutants by Electrospray Mass Spectrometry

2010 ◽  
Vol 20 (12) ◽  
pp. 1540-1545 ◽  
Author(s):  
Chong-Tian Yu ◽  
Yin-Long Guo ◽  
Long Lü ◽  
Yun-Hua Wang ◽  
Ping Yao ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Phase Stability ◽  
Electrospray Mass Spectrometry ◽  
Binding Pocket ◽  
Heme Binding

Mass spectrometric characterization of protein structures and protein complexes in condensed and gas phase

2017 ◽  
Vol 23 (6) ◽  
pp. 445-459 ◽  
Author(s):  
Yelena Yefremova ◽  
Bright D Danquah ◽  
Kwabena FM Opuni ◽  
Reham El-Kased ◽  
Cornelia Koy ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Electrospray Mass Spectrometry ◽  
Protein Complexes ◽  
Protein Structures ◽  
Three Dimensional ◽  
Amino Acid Sequences ◽  
Direct Access ◽  
Intact Protein

Proteins are essential for almost all physiological processes of life. They serve a myriad of functions which are as varied as their unique amino acid sequences and their corresponding three-dimensional structures. To fulfill their tasks, most proteins depend on stable physical associations, in the form of protein complexes that evolved between themselves and other proteins. In solution (condensed phase), proteins and/or protein complexes are in constant energy exchange with the surrounding solvent. Albeit methods to describe in-solution thermodynamic properties of proteins and of protein complexes are well established and broadly applied, they do not provide a broad enough access to life-science experimentalists to study all their proteins' properties at leisure. This leaves great desire to add novel methods to the analytical biochemist's toolbox. The development of electrospray ionization created the opportunity to characterize protein higher order structures and protein complexes rather elegantly by simultaneously lessening the need of sophisticated sample preparation steps. Electrospray mass spectrometry enabled us to translate proteins and protein complexes very efficiently into the gas phase under mild conditions, retaining both, intact protein complexes, and gross protein structures upon phase transition. Moreover, in the environment of the mass spectrometer (gas phase, in vacuo), analyte molecules are free of interactions with surrounding solvent molecules and, therefore, the energy of inter- and intramolecular forces can be studied independently from interference of the solvating environment. Provided that gas phase methods can give information which is relevant for understanding in-solution processes, gas phase protein structure studies and/or investigations on the characterization of protein complexes has rapidly gained more and more attention from the bioanalytical scientific community. Recent reports have shown that electrospray mass spectrometry provides direct access to six prime protein complex properties: stabilities, compositions, binding surfaces (epitopes), disassembly processes, stoichiometries, and thermodynamic parameters.

scholarly journals Protonation of curcumin triggers sequential double cyclization in the gas-phase: An electrospray mass spectrometry and DFT study

2019 ◽  
Vol 438 ◽  
pp. 107-114
Author(s):  
June Cyriac ◽  
Justin Paulose ◽  
Mathai George ◽  
R. Srinivas ◽  
Daryl Giblin ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Electrospray Mass Spectrometry ◽  
Dft Study
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