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Glutathione is a biologically abundant and redox active tripeptide that coordinates with metals. This study examines the change in binding conformation with relevant dications; Zn²⁺, Cu²⁺, and Fe²⁺.

 

Threshold collision-induced dissociation (TCID) and infrared multiple photon dissociation (IRMPD) spectroscopy are used to examine complexes of metal mono- and dications with amino acids and peptides. Trends in the results are elucidated.

 

A combination of IR multiple-photon dissociation (IRMPD) action spectroscopy and quantum chemical calculations was employed to investigate the [M,C,2H]⁺(M = Fe and Co) species.

 

A combination of infrared multiple-photon dissociation (IRMPD) action spectroscopy and quantum chemical calculations was employed to investigate the [M,C,2H]⁺(M = Ru and Rh) species.

 

In this feature article, I reflect on over 40 years of guided ion beam tandem mass spectrometry (GIBMS) studies involving atomic metal cations and their clusters throughout the periodic table. Studies that have considered the role of spin conservation (or lack thereof) are a primary focus, with a quantitative assessment of the effects examined. A need for state-specific studies of heavier elements is noted as is a more quantitative assessment of spin-orbit interactions in reactivity. Because GIBMS experiments explicitly evaluate the kinetic energy dependence of reactions over a wide range, several interesting and unusual observations are highlighted. More detailed studies of such unusual reaction events would be welcome. Activation of C-H bonds and ensuing C-C coupling events are reviewed, with future work encouraged. Finally, studies of lanthanides and actinides are examined with an eye on understanding the role of f orbitals in the chemistry, both as participants (or not) in the bonding and as sources/sinks of electron density. This area seems ripe for more quantitative experiments. 

Abstract Fragmentation studies of cationized amino acids and small peptides as studied using guided ion beam tandem mass spectrometry (GIBMS) are reviewed. After a brief examination of the key attributes of the GIBMS approach, results for a variety of systems are examined, compared, and contrasted. Cationization of amino acids, diglycine, and triglycine with alkali cations generally leads to dissociations in which the intact biomolecule is lost. Exceptions include most lithiated species as well as a few examples for sodiated and one example for potassiated species. Like the lithiated species, cationization by protons leads to numerous dissociation channels. Results for protonated glycine, cysteine, asparagine, diglycine, and a series of tripeptides are reviewed, along with the thermodynamic consequences that can be gleaned. Finally, the important physiological process of the deamidation of asparagine (Asn) residues is explored by the comparison of five dipeptides in which the C‐terminal partner (AsnXxx) is altered. The GIBMS thermochemistry is shown to correlate well with kinetic results from solution phase studies.