Ion mobility resolved photo‐fragmentation to discriminate protomers

Abstract

We show that, even if precise structure assignment based on molecular modeling is in principle difficult for large biomolecular assemblies, the combination of photo-fragmentation and IMS can help to identify the signature of protomer co-existence for a population of biomolecular ions in the gas phase. Such spectroscopic data are particularly suitable to follow conformational changes.

Structure and Charge Heterogeneity in Isomeric Au25(MBA)18 Nanoclusters—Insights from Ion Mobility and Mass Spectrometry

“…In the IMS-IMS operation mode, the ion gate at the end of DT1 is used to cut a “slice” in the ATD, thus letting through only the ions in a narrow arrival time range. This allows isomer selection. − The ATDs recorded in this mode give information about potential modifications of the ions after selection., namely, an ATD not consisting of a single peak centered at the selected drift time provides a signature of a change in the mobility of the ions, i.e., a change in their “surface-to-charge” ratio. This procedure was previously used to study isomerization, corresponding to a change of CCS, , but it is also clear from eq that a change in the charge q also affects the arrival time.…”

Radiation‐Induced Transfer of Charge, Atoms, and Energy within Isolated Biomolecular Systems

“… The influence of solvent is removed, leaving the intrinsic properties of the systems for direct experimental investigation. Experimental data can be compared to theoretical calculations, most often using quantum chemical methods. Mass spectrometric tools allow defining the initial state of a molecular system in terms of size, stoichiometry, temperature, charge, and tautomeric states. The final state can be probed by analyzing the mass‐to‐charge ( m/z ) ratio of ionic products formed after the interaction between the molecular system and ionizing radiation. Techniques such as ion mobility spectrometry or IR/UV hole burning spectroscopy are sensitive to the geometrical structure of molecular systems, and thus allow for selecting a given conformer (before interaction with a laser for instance [16,17] ) or tracing specific ionic products to one conformer [18] Last but not least, biological systems as large as intact viruses can be brought into the gas phase thanks to techniques such as electrospray (or nanospray) ionization or matrix‐assisted laser desorption ionization [19] …”

“…Techniques such as ion mobility spectrometry or IR/UV hole burning spectroscopy are sensitive to the geometrical structure of molecular systems, and thus allow for selecting a given conformer (before interaction with a laser for instance [16,17] ) or tracing specific ionic products to one conformer [18] …”

Autocatalysis in Eschenmoser Coupling Reactions

“…In this work, the intermediates in the ECR between 1 and 2 (Scheme 1) were monitored and characterized using electrospray ionization mass spectrometry (ESI‐MS). The sensitivity of mass spectrometry enables the detection of low‐concentration species, making it a tool of choice to detect and investigate reactive intermediates [23–27] . Along with online reaction monitoring, mass spectrometry offers a variety of add‐on methods to gain mechanistic insights [6,28–31] .…”