scholarly journals Photodegradation of Riboflavin under Alkaline Conditions: What can Gas-Phase Photolysis Tell Us About What Happens in Solution?

2021 ◽  
Author(s):  
Natalie G.K. Wong ◽  
Chris Rhodes ◽  
Caroline E.H. Dessent
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Direct Method ◽  
Photochemical Reactions ◽  
Solution Phase ◽  
Ionization Mass ◽  
Phase Reaction ◽  
Esi Ms ◽  
Alkaline Conditions ◽  
On Line

The application of electrospray ionization mass spectrometry (ESI-MS) as a direct method for detecting reactive intermediates is a technique of developing importance in the routine monitoring of solution-phase reaction pathways. Here, we utilize a novel on-line photolysis ESI-MS approach to detect the photoproducts of riboflavin in aqueous solution under mildly alkaline conditions. Riboflavin is a constituent of many food products, so its breakdown processes are of wide interest. Our on-line photolysis setup allows for solution-phase photolysis to occur within a syringe using UVA LEDs, immediately prior to being introduced into the mass spectrometer via ESI. Gas-phase photofragmentation studies via laser-interfaced mass spectrometry of deprotonated riboflavin, [RFH], the dominant solution-phase species under the conditions of our study, are presented alongside the solution-phase photolysis. The results obtained illustrate the extent to which gas-phase photolysis methods can inform our understanding of the corresponding solution-phase photochemistry. We determine that the solution-phase photofragmentation observed for [RFH] closely mirrors the gas-phase photochemistry, with the m/z 241 ion being the only major condensed-phase photoproduct. Further gas-phase photoproducts are observed at m/z 255, 212, and 145. The value of exploring both the gas- and solution-phase photochemistry to characterize photochemical reactions is discussed.

scholarly journals Photodegradation of Riboflavin under Alkaline Conditions: What Can Gas-Phase Photolysis Tell Us about What Happens in Solution?

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 6009
Author(s):  
Natalie G. K. Wong ◽  
Chris Rhodes ◽  
Caroline E. H. Dessent
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Direct Method ◽  
Photochemical Reactions ◽  
Solution Phase ◽  
Phase Reaction ◽  
Esi Ms ◽  
Routine Monitoring ◽  
Alkaline Conditions ◽  
On Line

The application of electrospray ionisation mass spectrometry (ESI-MS) as a direct method for detecting reactive intermediates is a technique of developing importance in the routine monitoring of solution-phase reaction pathways. Here, we utilise a novel on-line photolysis ESI-MS approach to detect the photoproducts of riboflavin in aqueous solution under mildly alkaline conditions. Riboflavin is a constituent of many food products, so its breakdown processes are of wide interest. Our on-line photolysis setup allows for solution-phase photolysis to occur within a syringe using UVA LEDs, immediately prior to being introduced into the mass spectrometer via ESI. Gas-phase photofragmentation studies via laser-interfaced mass spectrometry of deprotonated riboflavin, [RF − H]−, the dominant solution-phase species under the conditions of our study, are presented alongside the solution-phase photolysis. The results obtained illustrate the extent to which gas-phase photolysis methods can inform our understanding of the corresponding solution-phase photochemistry. We determine that the solution-phase photofragmentation observed for [RF − H]− closely mirrors the gas-phase photochemistry, with the dominant m/z 241 condensed-phase photoproduct also being observed in gas-phase photodissociation. Further gas-phase photoproducts are observed at m/z 255, 212, and 145. The value of exploring both the gas- and solution-phase photochemistry to characterise photochemical reactions is discussed.

Do electrospray mass spectra reflect the ligand binding state of proteins in solution?

2005 ◽  
Vol 83 (11) ◽  
pp. 1953-1960 ◽  
Author(s):  
Belal M Hossain ◽  
Douglas A Simmons ◽  
Lars Konermann
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Protein Interactions ◽  
Noncovalent Complex ◽  
Deuterium Exchange ◽  
Solution Phase ◽  
Hydrogen Deuterium Exchange ◽  
Esi Ms ◽  
Protein Ions ◽  
Hydrogen Deuterium

Electrospray ionization (ESI) mass spectrometry (MS) has become a popular tool for monitoring ligand–protein and protein–protein interactions. Due to the "gentle" nature of the ionization process, it is often possible to transfer weakly bound complexes into the gas phase, thus making them amenable to MS detection. One problem with this technique is the potential occurrence of fragmentation events during ESI. Also, some analytes tend to cluster together during ionization, thus forming nonspecific gas-phase assemblies that do not represent solution-phase complexes. In this work, we implemented a hydrogen–deuterium exchange (HDX) approach that can reveal whether or not the free and (or) bound constituents of a complex observed in ESI-MS reflect the binding situation in solution. Proteins are subjected to ESI immediately following an isotopic labeling pulse; only ligand-free and ligand-bound protein ions that were formed directly from the corresponding solution-phase species showed different HDX levels. Using myoglobin as a model system, it is demonstrated that this approach can readily distinguish scenarios where the heme–protein interactions were disrupted in solution from those where dissociation of the complex occurred in the gas phase. Experiments on cytochrome c strongly suggest that dimeric protein ions observed in ESI-MS reflect aggregates that were formed in solution.Key words: electrospray mass spectrometry, ligand–protein interaction, noncovalent complex, hydrogen–deuterium exchange, protein folding.

On-line chiral analysis using the kinetic method

The Analyst ◽  
2016 ◽  
Vol 141 (8) ◽  
pp. 2441-2446 ◽  
Author(s):  
Ryan M. Bain ◽  
Xin Yan ◽  
Shannon A. Raab ◽  
Stephen T. Ayrton ◽  
Tawnya G. Flick ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Kinetic Method ◽  
Enantiomeric Excess ◽  
Solution Phase ◽  
Chiral Analysis ◽  
Tandem Mass ◽  
Phase Reaction ◽  
On Line

Chiral analysis of constituents in solution-phase reaction mixtures can be performed by tandem mass spectrometry using the kinetic method to determine the enantiomeric excess (ee).

Electrospray ionization mass spectrometry and on-line capillary zone electrophoresis - mass spectrometry for the characterization of citrate synthase

1999 ◽  
Vol 77 (11) ◽  
pp. 1752-1760 ◽  
Author(s):  
Mark E McComb ◽  
Lynda J Donald ◽  
Hélène Perreault
Keyword(s):  
Mass Spectrometry ◽  
Electrospray Ionization ◽  
Electrospray Ionization Mass Spectrometry ◽  
Citrate Synthase ◽  
Time Of Flight ◽  
Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Wild Type ◽  
Esi Ms ◽  
On Line

The enzyme citrate synthase from E. coli is a protein with a molecular weight (Mr) of 47 885 Da (wild type). This enzyme has been studied extensively, and its amino acid sequence has been characterized. This model protein has been used in this work for development and validation of methods involving capillary electrophoresis (CE) and electrospray ionization mass spectrometry (ESI-MS). The Mr determinations were conducted using sample infusion ESI-MS, and the tryptic digestion products of wild-type citrate synthase were characterized by on-line CE-ESI-MS coupled with a sheathless interface. On-line experiments were conducted on two different mass spectrometers, a Quattro-LC triple quadrupole instrument equipped with a Z-SprayTM source (Micromass), and a reflecting time-of-flight (TOF) mass spectrometer built in-house in the Time-of-Flight Laboratory, Department of Physics, University of Manitoba. This is the first article to be written on the interfacing of a Z-SprayTM source with CE. Unmodified fused silica capillaries gold-coated sheathless interfaces were used. The on-line CE separations yielded theoretical plate numbers greater than 104 on average. Selected ion electrophorograms (SIE) of the tryptic peptides recorded on the Quattro-LC displayed S/N ratios ranging from ca. 14 to 120 on raw data. These SIE enabled identification of each peptide. The use of reflecting time-of-flight mass spectrometry (TOFMS) afforded mass resolution values of ca. 6000 (m/deltamFWHM), which enabled isotopic resolution of the peptide components. CE-ESI-MS and CE-ESI-TOFMS experiments enabled the generation of a complete tryptic map of citrate synthase.Key words: capillary electrophoresis, electrospray ionization, mass spectrometry, citrate synthase, tryptic digestion, triple quadrupole analyzer, time-of-flight analyzer.

Sign in / Sign up

Export Citation Format

Share Document