Investigating Vibrational Heat Capacities of Gas-Phase Biomolecular Ions For Use in Determining Ion Thermochemistry
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Date
2024
Authors
Paris, Lawren
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
As the field of native mass spectrometry grows, there is increasing interest in quantitatively determining ion dissociation, unfolding thermochemistry, and kinetics using commonly available mass spectrometers. In particular, understanding the relationship between ion activation, internal energy, and temperature will likely be necessary for detailed structural interpretation of Collision Induced Dissociation and Collision Induced Unfolding data for native biomolecular ions and their complexes. Here, we use quantum computational theory to predict heat capacities for a variety of model biomolecular structures and report effects of level of theory, basis set, ion secondary structure, and biomolecule type on vibrational heat capacity per vibrational degree of freedom from 100 to 3000 K. On a degree-of-freedom basis, these values are remarkably invariant within each biomolecule type and can be used to estimate heat capacities of much larger biomolecular ions. We also explore effects of heat capacity ion heating, cooling, and internal energy distribution as a function of time use a home-built program (IonSPA). We observe that these internal energy distributions can be nearly Boltzmann for larger ions and at higher temperatures achieved through collisional heating after a brief (few-μs) induction period.
Description
78 pages
Keywords
Chemistry, Native Ion Mobility Mass Spectrometry, Computational Chemsitry, Vibrational Heat Capacity, Ion Simulations of the Physics of Activation