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Posttranslational modifications (PTMs) play vital roles in cellular homeostasis and are implicated in various pathological conditions. This work uses two ion mobility spectrometry-mass spectrometry (IMS-MS) modalities, drift-tube IMS (DT-IMS) and trapped IMS (TIMS), to characterize three important nonenzymatic PTMs that induce no mass loss: l/d isomerization, aspartate/isoaspartate isomerization, and / proline isomerization. These PTMs are assessed in a single peptide system, the recently discovered pleurin peptides, Plrn2, from . We determine that the DT-IMS-MS/MS can capture and locate asparagine deamidation into aspartate and its subsequent isomerization to isoaspartate, a key biomarker for age-related diseases. Additionally, nonenzymatic peptide cleavage via in-source fragmentation is evaluated for differences in the intensities and patterns of fragment peaks between these PTMs. Peptide fragments resulting from in-source fragmentation, preceded by peptide denaturation by liquid chromatography (LC) mobile phase, exhibited / proline isomerization. Finally, the effects of differing the fragmentation voltage at the source and solution-based denaturation conditions on in-source fragmentation profiles are evaluated, confirming that LC denaturation and in-source fragmentation profoundly impact N-terminal peptide bond cleavages of Plrn2 and the structures of their fragment ions. With that, LC-IMS-MS/MS coupled with in-source fragmentation could be a robust method to identify three important posttranslational modifications: l/d isomerization, Asn-deamidation leading to Asp/IsoAsp isomerization, and / proline isomerization.
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http://dx.doi.org/10.1021/jasms.3c00092 | DOI Listing |
J Am Soc Mass Spectrom
August 2025
Department of Forensic Science, Trent University, Peterborough, Ontario K9L 0G2, Canada.
The use of ambient ionization mass spectrometry (AI-MS) to aid in the preliminary screening of seized drug evidence has steadily increased over the past two decades. Unlike gas chromatography-mass spectrometry (GC-MS), where electron ionization using a single quadrupole analyzer is commonplace, a wide range of ionization sources and mass spectrometers can be used in AI-MS. Differences in instrument configuration can lead to substantial variability in the mass spectral data obtained.
View Article and Find Full Text PDFMass Spectrom Rev
August 2025
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan.
Because matrix-assisted laser desorption/ionization in-source decay (MALDI-ISD) induces selective cleavage on the peptide backbone, this technique allows reliable identification of peptides and proteins. In the last 15 years, several new matrices have been developed that more efficiently induce MALDI-ISD, opening new research avenues. Fragmentation of peptides by MALDI-ISD can be divided into two categories: reducing and oxidizing matrices induce selective cleavage of N-Cα and Cα-C bonds, respectively.
View Article and Find Full Text PDFJ Am Soc Mass Spectrom
September 2025
Department of Chemistry and Biochemistry, University of Toledo, Toledo, Ohio 43606, United States.
Microcystins (MCs) are hepatotoxic cyclic peptides produced by cyanobacteria, with MC-RR being one of the most polar and commonly detected MC congeners in water collected during cyanobacterial harmful algal blooms (cHABs). Microguanidines (MGDs) are sulfated metabolites produced by sp. that have not been reported during Lake Erie cHABs.
View Article and Find Full Text PDFAnal Chim Acta
October 2025
Mass Spectrometry Research Center, Vanderbilt University, Nashville, TN, USA; Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA; Department of Biochemistry, Vanderbilt University, Nashville, TN, USA; Department of Chemistry, Vanderbilt University, Nashville, TN,
Background: We have developed a new class of dual polarity molecules for matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) capable of acquiring 5 μm pixel sizes with high sensitivity toward polar lipids and metabolites. Aminated cinnamic acid analogs (ACAAs) are vacuum stable, have high extinction coefficients at 355 nm, are highly sensitive to polar lipids, have low toxicity, and are affordable. Current molecules used for high spatial resolution MALDI IMS of polar lipids have shown great success, but are plagued with issues such as low sensitivity at high spatial resolution, vacuum instability, and/or high toxicity.
View Article and Find Full Text PDFJ Am Soc Mass Spectrom
August 2025
Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States.
The ability to differentiate disaccharide isomers within plant tissues, in a spatially resolved fashion, is required to render a more precise understanding of their biological function within these systems. In this study, we report drift tube ion mobility spectrometry (DTIMS) and trapped ion mobility spectrometry (TIMS) profiling of two important plant disaccharides, sucrose and trehalose, along with their 6-phosphate derivatives. We then map these disaccharides in poplar root and soybean root nodules using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) with premass analysis TIMS.
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