Structural characterizations of protonated homodimers of amino acids: Revealed by infrared multiple photon dissociation (IRMPD) spectroscopy and theoretical calculations

2018 ◽  
Vol 29 (9) ◽  
pp. 1333-1339 ◽  
Author(s):  
Lifu Ma ◽  
Juan Ren ◽  
Ruxia Feng ◽  
Kailin Zhang ◽  
Xianglei Kong
Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 5152
Author(s):  
Yingying Shi ◽  
Mengying Du ◽  
Juan Ren ◽  
Kailing Zhang ◽  
Yicheng Xu ◽  
...  

In recent years, methods based on photodissociation in the gas phase have become powerful means in the field of chiral analysis. Among them, infrared multiple photon dissociation (IRMPD) spectroscopy is a very attractive one, since it can provide valuable spectral and structural information of chiral complexes in addition to chiral discrimination. Experimentally, the method can be fulfilled by the isolation of target diastereomeric ions in an ion trap followed by the irradiation of a tunable IR laser. Chiral analysis is performed by comparing the difference existing in the spectra of enantiomers. Combined with theoretical calculations, their structures can be further understood on the molecular scale. By now, lots of chiral molecules, including amino acids and peptides, have been studied with the method combined with theoretical calculations. This review summarizes the relative experimental results obtained, and discusses the limitation and prospects of the method.


2021 ◽  
Vol 23 (5) ◽  
pp. 3627-3636
Author(s):  
Ethan M. Cunningham ◽  
Thomas Taxer ◽  
Jakob Heller ◽  
Milan Ončák ◽  
Christian van der Linde ◽  
...  

The structures, along with solvation evolution, of size-selected Zn+(H2O)n (n = 2–35) complexes have been determined by combining infrared multiple photon photodissociation (IRMPD) spectroscopy and density functional theory.


2014 ◽  
Vol 16 (44) ◽  
pp. 24223-24234 ◽  
Author(s):  
Michael Burt ◽  
Kathleen Wilson ◽  
Rick Marta ◽  
Moaraj Hasan ◽  
W. Scott Hopkins ◽  
...  

The gas-phase structures of two halide-bound phenylalanine anions (PheX−, X = Cl− or Br−) and five fluorinated derivatives have been identified using infrared multiple photon dissociation (IRMPD) spectroscopy.


Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6546
Author(s):  
Ruxia Feng ◽  
Yicheng Xu ◽  
Xianglei Kong

Although metal cations are prevalent in biological media, the species of multi-metal cationized biomolecules have received little attention so far. Studying these complexes in isolated state is important, since it provides intrinsic information about the interaction among them on the molecular level. Our investigation here demonstrates the unexpected structural diversity of such species generated by a matrix-assisted laser desorption ionization (MALDI) source in the gas phase. The photodissociation spectroscopic and theoretical study reflects that the co-existing isomers of [Arg+Rb+K−H]+ can have energies ≥95 kJ/mol higher than that of the most stable one. While the result can be rationalized by the great isomerization energy barrier due to the coordination, it strongly reminds us to pay more attention to their structural diversities for multi-metalized fundamental biological molecules, especially for the ones with the ubiquitous alkali metal ions.


2018 ◽  
Vol 20 (48) ◽  
pp. 30428-30436 ◽  
Author(s):  
Sung-Sik Lee ◽  
Jae-ung Lee ◽  
Ju Hyeon Oh ◽  
Soojin Park ◽  
Yin Hong ◽  
...  

d-/l-Isoleucine chirality could be differentiated using IRMPD spectroscopy, ion-mobility mass spectrometry, and DFT calculations for the permethylated β-cyclodextrin non-covalent complex.


2018 ◽  
Vol 25 (1) ◽  
pp. 112-121 ◽  
Author(s):  
Andrii Piatkivskyi ◽  
Justin Kai-Chi Lau ◽  
Giel Berden ◽  
Jos Oomens ◽  
Alan C Hopkinson ◽  
...  

Two types of radical cations of tryptophan—the π-radical cation and the protonated tryptophan-N radical—have been studied in dipeptides AW and WA. The π-radical cation produced by removal of an electron during collision-induced dissociation of a ternary Cu(II) complex was only observed for the AW peptide. In the case of WA, only the ion corresponding to the loss of ammonia, [WA–NH3] •+, was observed from the copper complex. Both protonated tryptophan-N radicals were produced by N-nitrosylation of the neutral peptides followed by transfer to the gas phase via electrospray ionization and subsequent collision-induced dissociation. The regiospecifically formed N• species were characterized by infrared multiple-photon dissociation spectroscopy which revealed that the WA tryptophan-N• radical remains the nitrogen radical, while the AW nitrogen radical rearranges into the π-radical cation. These findings are supported by the density functional theory calculations that suggest a relatively high barrier for the radical rearrangement (N• to π) in WA (156.3 kJ mol−1) and a very low barrier in AW (6.1 kJ mol−1). The facile hydrogen atom migration in the AW system is also supported by the collision-induced dissociation of the tryptophan-N radical species that produces fragments characteristic of the tryptophan π-radical cation. Gas-phase ion–molecule reactions with n-propyl thiol have also been used to differentiate between the π-radical cations (react by hydrogen abstraction) and the tryptophan-N• species (unreactive) of AW.


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