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Threshold collision-induced dissociation of conformations selected by ion mobility spectrometry is described as a method to determine their absolute relative energies. Here, the method is demonstrated with the cis and trans conformers of the protonated tetrapeptide, Gly-Pro-Gly-Gly, which differ in the orientation of the peptide bond at the proline residue. The trans conformation was found to be more stable than the cis conformation by 4.5 ± 2.5 kJ mol at 0 K. Heating the molecule anneals it to the cis conformer, indicating it has a lower Gibbs energy at higher temperatures. These results are compared to theoretical values calculated here and from the literature. This experimental analysis is the first quantitative measurement of the relative stability of the conformers of a protonated peptide in the gas phase, which has far-reaching impacts on the selection of theoretical methods to describe the energetics of these systems.
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http://dx.doi.org/10.1002/cphc.202500080 | DOI Listing |
J Am Soc Mass Spectrom
September 2025
Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States.
The escalating prevalence and diversity of fentanyl analogues poses an immediate concern for the global community. Fentanyl and its analogues are the primary contributors to both fatal and nonfatal overdoses in the United States. The most recent instances of fentanyl-related overdoses have been attributed to the illicit production of fentanyl, characterized by its exceptionally potent nature.
View Article and Find Full Text PDFAnal Chem
September 2025
Department of Chemistry, The University of Akron, Akron, Ohio 44325, United States.
Tires are complex polymeric materials composed of rubber elastomers (both natural and synthetic), fillers, steel wire, textiles, and a range of antioxidant and curing systems. These constituents are distributed differently among the various tire parts, which are classified based on their function and proximity to the rim. This study presents a rapid and sensitive approach for the characterization of tire components using mild thermal desorption/pyrolysis (TDPy) coupled to direct analysis in real-time mass spectrometry (DART-MS).
View Article and Find Full Text PDFAnal Chem
September 2025
Laboratory of Organic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland.
DNA-encoded libraries have become widely used in drug discovery, and several different setups to link chemical compounds to DNA have been employed in the field, including single-stranded and double-stranded DNA tags as well as a variety of linker chemistries. In our previous study, we observed distinct differences in binding affinities between ligands coupled either to single-stranded or double-stranded DNA; however, the molecular basis for these differences remained unclear. Here, we present a native ion mobility mass spectrometry approach that incorporates gas- and solution-phase activation techniques to systematically investigate these differences, specifically the impact of DNA tags on binding performance in protein-ligand interactions.
View Article and Find Full Text PDFPLoS One
September 2025
Departamento de Biología, Escuela de Ciencias e Ingeniería, Universidad del Rosario, Bogotá, Colombia.
Honey bees (Apis mellifera) are essential pollinators threatened by sublethal effects of pesticides such as imidacloprid, a widely used neonicotinoid that disrupts the central nervous system. However, many of the systemic effects are poorly understood, especially on the physiological homeostasis of the honey bee. We evaluated the effects of oral administration of imidacloprid and the flavonol rutin on the properties of extracellular fluid (ECF) in Apis mellifera.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
September 2025
Soft Matter Sciences and Engineering, CNRS, École supérieure de Physique et de Chimie Industrielles de la Ville de Paris, Université Paris Sciences et Lettres, Sorbonne Université, Paris 75005, France.
The sliding motion of aqueous droplets on hydrophobic surfaces leads to charge separation at the trailing edge, with implications from triple-line friction to hydrovoltaic energy generation. Charges deposited on the solid surface have been attributed to ions or electrons ripped off from the liquid drop. However, the dynamics and exact physicochemical nature of these surface-trapped charges remains poorly explored.
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