scholarly journals Electrostatically Tuning the Photodissociation of the Irgacure 2959 Photoinitiator in the Gas Phase by Cation Binding

2021 ◽  
Vol 143 (5) ◽  
pp. 2331-2339
Author(s):  
Samuel J. P. Marlton ◽  
Benjamin I. McKinnon ◽  
Nicholas S. Hill ◽  
Michelle L. Coote ◽  
Adam J. Trevitt
Keyword(s):  
Gas Phase ◽  
Cation Binding

Metal Cation Binding to Gas-Phase Pentaalanine: Divalent Ions Restructure the Complex

2012 ◽  
Vol 117 (6) ◽  
pp. 1094-1101 ◽  
Author(s):  
Robert C. Dunbar ◽  
Jeffrey D. Steill ◽  
Nicolas C. Polfer ◽  
Jos Oomens
Keyword(s):  
Gas Phase ◽  
Metal Cation ◽  
Cation Binding ◽  
Divalent Ions

scholarly journals DNA and RNA Telomeric G-Quadruplexes: What Topology Features Can be Inferred from Ion Mobility Mass Spectrometry?

2019 ◽  
Author(s):  
Valentina D’Atri ◽  
Valerie Gabelica
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Ion Mobility Spectrometry ◽  
Ion Mobility ◽  
Native Mass Spectrometry ◽  
Cation Binding ◽  
Telomeric Dna ◽  
Dna And Rna ◽  
G Quadruplex ◽  
Multiple Structures

Maintenance of the telomeres is key to chromosome integrity and cell proliferation. The G-quadruplex structures formed by telomeric DNA and RNA (TTAGGG and UUAGGG repeats, respectively) are key to this process. However, because these sequences are particularly polymorphic, solving high-resolution structures is not always possible, and there is a need for new methodologies to characterize the multiple structures coexisting in solution. In this context, we evaluated whether ion mobility spectrometry coupled to native mass spectrometry could help separate and assign the G-quadruplex topologies. We explored the circular dichroism spectra, multimer formation, cation binding, and ion mobility spectra of several 4-repeat and 8-repeat telomeric DNA and RNA sequences, both in NH<sub>4</sub><sup>+</sup> and in K<sup>+</sup>. In 1 mM K<sup>+</sup> and 100 mM trimethylammonium acetate, all RNAs fold intramolecularly (no multimer). In 8-repeat sequences, the subunits are not independent: in DNA the first subunit disfavors the folding of the second one, whereas in RNA the two subunits fold cooperatively via cation-mediated stacking. Ion mobility spectrometry shows that gas-phase structures keep a memory of the solution ones, but not identical. At the native charge states, the loops can rearrange in a variety of ways (unless they are constrained by pre-formed hydrogen bonds), thereby wrapping the core and masking the strand arrangements. Our study highlights that, to progress towards structural assignment from IM-MS experiments, deeper understanding of the solution-to-gas-phase rearrangement mechanisms is warranted. <br>

scholarly journals DNA and RNA Telomeric G-Quadruplexes: What Topology Features Can be Inferred from Ion Mobility Mass Spectrometry?

2019 ◽  
Author(s):  
Valentina D’Atri ◽  
Valerie Gabelica
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Ion Mobility Spectrometry ◽  
Ion Mobility ◽  
Native Mass Spectrometry ◽  
Cation Binding ◽  
Telomeric Dna ◽  
Dna And Rna ◽  
G Quadruplex ◽  
Multiple Structures

Maintenance of the telomeres is key to chromosome integrity and cell proliferation. The G-quadruplex structures formed by telomeric DNA and RNA (TTAGGG and UUAGGG repeats, respectively) are key to this process. However, because these sequences are particularly polymorphic, solving high-resolution structures is not always possible, and there is a need for new methodologies to characterize the multiple structures coexisting in solution. In this context, we evaluated whether ion mobility spectrometry coupled to native mass spectrometry could help separate and assign the G-quadruplex topologies. We explored the circular dichroism spectra, multimer formation, cation binding, and ion mobility spectra of several 4-repeat and 8-repeat telomeric DNA and RNA sequences, both in NH<sub>4</sub><sup>+</sup> and in K<sup>+</sup>. In 1 mM K<sup>+</sup> and 100 mM trimethylammonium acetate, all RNAs fold intramolecularly (no multimer). In 8-repeat sequences, the subunits are not independent: in DNA the first subunit disfavors the folding of the second one, whereas in RNA the two subunits fold cooperatively via cation-mediated stacking. Ion mobility spectrometry shows that gas-phase structures keep a memory of the solution ones, but not identical. At the native charge states, the loops can rearrange in a variety of ways (unless they are constrained by pre-formed hydrogen bonds), thereby wrapping the core and masking the strand arrangements. Our study highlights that, to progress towards structural assignment from IM-MS experiments, deeper understanding of the solution-to-gas-phase rearrangement mechanisms is warranted. <br>

Diarylferrocene tweezers for cation binding

2015 ◽  
Vol 17 (37) ◽  
pp. 23917-23923 ◽  
Author(s):  
Carlos F. R. A. C. Lima ◽  
Ana M. Fernandes ◽  
André Melo ◽  
Luís M. Gonçalves ◽  
Artur M. S. Silva ◽  
...  
Keyword(s):  
Gas Phase ◽  
Molecular Shape ◽  
Cation Binding ◽  
Molecular Tweezers ◽  
Strong Binding ◽  
Torsional Potentials

Diarylferrocenes can act as molecular tweezers of cations. Their unique molecular shape and low torsional potentials allow for strong binding of small cations in the gas phase.

scholarly journals Biomolecule structure characterization in the gas phase using mass spectrometry

2002 ◽  
Vol 16 (2) ◽  
pp. 71-79 ◽  
Author(s):  
Brian Bothner ◽  
Laurie Carmitchel ◽  
Kristin Staniszewski ◽  
Martin Sonderegger ◽  
Gary Siuzdak
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Cation Binding ◽  
Structure Characterization ◽  
Alkali Cation ◽  
Desorption Ionization ◽  
Fab Mass Spectrometry ◽  
Deuterated Analog ◽  
Bidentate Complex ◽  
Cation Complexes

Carbohydrate/cation interactions were examined in the gas phase using mass spectrometry and the results were compared with computer generated models of the complexes. Monosaccharide/alkali cation complexes of five carbohydrates, D-fructose, D-glucose, D-galactose, D-mannose, and a deuterated analog of D-glucose, 6,6-D-glucose-d2, were studied. Among the technuques used in this effort were electrospray ionization (ESI), desorption/ionization on silicon (DIOS), matrix-assisted laser desorption/ionization (MALDI) and fast atom/ion bombardment (FAB) mass spectrometry. A series of ESI, DIOS, MALDI and FAB-MS experiments were used to obtain relative cation binding preferences of each monosaccharide. Heterodimers of 6,6-D-glucose-d2formed with each of the monosaccharides show that Na+binding for D-fructose, D-mannose and D-galactose is similar, while D-glucose was 25% weaker. Modeling studies and energy minimization calculations on the alpha and beta forms of the monosaccharide alkali cation complexes are consistent with the experimental data and indicate that D-fructose, D-galactose, and D-mannose undergo tridentate and tetradentate binding with Na+and Li+while D-glucose would only form a bidentate complex.

scholarly journals Relative glycosidic bond stabilities of naturally occurring methylguanosines: 7-methylation is intrinsically activating

2018 ◽  
Vol 25 (1) ◽  
pp. 16-29 ◽  
Author(s):  
Zachary J Devereaux ◽  
Y Zhu ◽  
MT Rodgers
Keyword(s):  
Nucleic Acid ◽  
Gas Phase ◽  
Excision Repair ◽  
Inverse Correlation ◽  
Sodium Cation ◽  
Cation Binding ◽  
Glycosidic Bond ◽  
Proton Affinities ◽  
Chemical Complexity ◽  
Naturally Occurring

The frequency and diversity of posttranscriptional modifications add an additional layer of chemical complexity beyond canonical nucleic acid sequence. Methylations are particularly frequently occurring and often highly conserved throughout the kingdoms of life. However, the intricate functions of these modified nucleic acid constituents are often not fully understood. Systematic foundational research that reduces systems to their minimum constituents may aid in unraveling the complexities of nucleic acid biochemistry. Here, we examine the relative intrinsic N-glycosidic bond stabilities of guanosine and five naturally occurring methylguanosines (O2′-, 1-, 7-, N2,N2-di-, and N2,N2,O2′-trimethylguanosine) probed by energy-resolved collision-induced dissociation tandem mass spectrometry and complemented with quantum chemical calculations. Apparent glycosidic bond stability is generally found to increase with increasing methyl substitution (canonical < mono- < di- < trimethylated). Many biochemical transformations, including base excision repair mechanisms, involve protonation and/or noncovalent interactions to increase nucleobase leaving-group ability. The protonated gas-phase methylguanosines require less activation energy for glycosidic bond cleavage than their sodium cationized forms. However, methylation at the N7 position intrinsically weakens the glycosidic bond of 7-methylguanosine more significantly than subsequent cationization, and thus 7-methylguanosine is suggested to be under perpetually activated conditions. N7 methylation also alters the nucleoside geometric preferences relative to the other systems, including the nucleobase orientation in the neutral form, sugar puckering in the protonated form, and the preferred protonation and sodium cation binding sites. All of the methylated guanosines examined here are predicted to have proton affinities and gas-phase basicities that exceed that of canonical guanosine. Additionally, the proton affinity and gas-phase basicity trends exhibit a roughly inverse correlation with the apparent glycosidic bond stabilities.

scholarly journals Electrostatically Tuning the Photodissociation of the Irgacure 2959 Photoinitiator in the Gas Phase by Cation Binding

2020 ◽  
Author(s):  
Samuel Marlton ◽  
Benjamin I. McKinnon ◽  
Nicholas Hill ◽  
Michelle Coote ◽  
Adam Trevitt
Keyword(s):  
Electric Field ◽  
Gas Phase ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Cation Binding ◽  
Type I ◽  
Computational Investigation ◽  
Norrish Type ◽  
Td Dft ◽  
Cation Complexes

<div><div><div><p>Our paper reports a combined experimental and computational investigation of the electrostatic tuning of Irgacure 2959, a Norrish-type I photoinitiator, in the presence of bound cations (H<sup>+</sup> , Li<sup>+</sup> , Na<sup>+</sup> , K<sup>+</sup> , Zn<sup>2+</sup> , Ca<sup>2+</sup> and Mg2+). Laser photodissociation action spectroscopy is deployed to acquire photodissociation spectra of mass- selected cation complexes. Quantum chemical calculations (TD-DFT and SCS-CC2) reveal that the cations are acting as point charges such that shifts of the key ππ* and nπ* states can be modelled as perturbations by an oriented electric field (OEF). The model agrees with the experimental photodissociation action spectra.</p></div></div></div>

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