scholarly journals Toward understanding the ionization mechanism of matrix‐assisted ionization using mass spectrometry experiment and theory

2019 ◽  
Vol 35 (S1) ◽  
Author(s):  
Chuping Lee ◽  
Ellen D. Inutan ◽  
Jien Lian Chen ◽  
Mutanu M. Mukeku ◽  
Steffen M. Weidner ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Ionization Mechanism ◽  
Mass Spectrometry Experiment

scholarly journals Surface acoustic wave nebulization improves compound selectivity of low-temperature plasma ionization for mass spectrometry

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andreas Kiontke ◽  
Mehrzad Roudini ◽  
Susan Billig ◽  
Amarghan Fakhfouri ◽  
Andreas Winkler ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Low Temperature ◽  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Ionization Mechanism ◽  
Low Temperature Plasma ◽  
Ambient Conditions ◽  
Temperature Plasma ◽  
Plasma Ionization ◽  
Surface Acoustic Wave Nebulization

AbstractMass spectrometry coupled to low-temperature plasma ionization (LTPI) allows for immediate and easy analysis of compounds from the surface of a sample at ambient conditions. The efficiency of this process, however, strongly depends on the successful desorption of the analyte from the surface to the gas phase. Whilst conventional sample heating can improve analyte desorption, heating is not desirable with respect to the stability of thermally labile analytes. In this study using aromatic amines as model compounds, we demonstrate that (1) surface acoustic wave nebulization (SAWN) can significantly improve compound desorption for LTPI without heating the sample. Furthermore, (2) SAWN-assisted LTPI shows a response enhancement up to a factor of 8 for polar compounds such as aminophenols and phenylenediamines suggesting a paradigm shift in the ionization mechanism. Additional assets of the new technique demonstrated here are (3) a reduced analyte selectivity (the interquartile range of the response decreased by a factor of 7)—a significant benefit in non-targeted analysis of complex samples—and (4) the possibility for automated online monitoring using an autosampler. Finally, (5) the small size of the microfluidic SAWN-chip enables the implementation of the method into miniaturized, mobile LTPI probes.

scholarly journals Chemical proteomics reveals target selectivity of clinical Jak inhibitors in human primary cells

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
H. Christian Eberl ◽  
Thilo Werner ◽  
Friedrich B. Reinhard ◽  
Stephanie Lehmann ◽  
Douglas Thomson ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Protein Kinases ◽  
Kinase Inhibitors ◽  
Dissociation Constants ◽  
Peripheral Blood Mononuclear ◽  
Mass Spectrometry Experiment ◽  
Chemical Proteomics ◽  
Human Primary Cells ◽  
Lipid Kinases ◽  
Single Mass

Abstract Kinobeads are a set of promiscuous kinase inhibitors immobilized on sepharose beads for the comprehensive enrichment of endogenously expressed protein kinases from cell lines and tissues. These beads enable chemoproteomics profiling of kinase inhibitors of interest in dose-dependent competition studies in combination with quantitative mass spectrometry. We present improved bead matrices that capture more than 350 protein kinases and 15 lipid kinases from human cell lysates, respectively. A multiplexing strategy is suggested that enables determination of apparent dissociation constants in a single mass spectrometry experiment. Miniaturization of the procedure enabled determining the target selectivity of the clinical BCR-ABL inhibitor dasatinib in peripheral blood mononuclear cell (PBMC) lysates from individual donors. Profiling of a set of Jak kinase inhibitors revealed kinase off-targets from nearly all kinase families underpinning the need to profile kinase inhibitors against the kinome. Potently bound off-targets of clinical inhibitors suggest polypharmacology, e.g. through MRCK alpha and beta, which bind to decernotinib with nanomolar affinity.

Effect of thenardite on the direct detection of aromatic amino acids: implications for the search for life in the solar system

2009 ◽  
Vol 8 (4) ◽  
pp. 291-300 ◽  
Author(s):  
C. Doc Richardson ◽  
Nancy W. Hinman ◽  
Jill R. Scott
Keyword(s):  
Mass Spectrometry ◽  
Amino Acids ◽  
Amino Acid ◽  
Aromatic Amino Acids ◽  
Laser Desorption ◽  
Ionization Mechanism ◽  
Side Chains ◽  
Ion Cyclotron Resonance ◽  
Laser Desorption Mass Spectrometry ◽  
Aromatic Side Chains

AbstractWith the discovery of Na-sulphate minerals on Mars and Europa, recent studies using these minerals have focused on their ability to assist in the detection of bio/organic signatures. This study further investigates the ability of thenardite (Na2SO4) to effectively facilitate the ionization and identification of aromatic amino acids (phenylalanine, tyrosine and tryptophan) using a technique called geomatrix-assisted laser desorption/ionization in conjunction with a Fourier transform ion cyclotron resonance mass spectrometry. This technique is based on the ability of a mineral host to facilitate desorption and ionization of bio/organic molecules for detection. Spectra obtained from each aromatic amino acid alone and in combination with thenardite show differences in ionization mechanism and fragmentation patterns. These differences are due to chemical and structural differences between the aromatic side chains of their respective amino acid. Tyrosine and tryptophan when combined with thenardite were observed to undergo cation-attachment ([M+Na]+), due to the high alkali ion affinity of their aromatic side chains. In addition, substitution of the carboxyl group hydrogen by sodium led to formation of [M-H+Na]Na+ peaks. In contrast, phenylalanine mixed with thenardite showed no evidence of Na+ attachment. Understanding how co-deposition of amino acids with thenardite can affect the observed mass spectra is important for future exploration missions that are likely to use laser desorption mass spectrometry to search for bio/organic compounds in extraterrestrial environments.

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