IR spectroscopy of cationized aliphatic amino acids: Stability of charge-solvated structure increases with metal cation size

Effects of Alkali Metal Ion Cationization on Fragmentation Pathways of Triazole-Epothilone

“…Thus, metal cations are frequently selected and used as promoters in lots of catalytic systems to improve both activity and selectivity [1]. Since the introduction of soft ionization method of electrospray ionization (ESI) [2], the noncovalent interactions between the metal ions and organic or biological molecules in the gas phase have attracted much interest [3][4][5][6][7][8][9][10][11][12]. The formation of these complexes has been utilized as a useful tool for enhancing the identification and characterization of some trace molecules.…”

“…With methods of tandem mass spectrometry (MS), infrared multiple photon dissociation action spectroscopy, H/D exchange, ion mobility spectrometry and theoretical calculations, structures of different metal cationized molecules, including amino acids and peptides, are investigated systematically [4][5][6][7][8][9][10][11][12]. For example, molecules of arginine cationized by alkali metal ions can form salt bridged structures in the gas phase [4]; with increasing sizes of the bound alkali metal ions, most amino acid molecules would more likely choose zwitterionic structures [4,5].…”

“…For example, molecules of arginine cationized by alkali metal ions can form salt bridged structures in the gas phase [4]; with increasing sizes of the bound alkali metal ions, most amino acid molecules would more likely choose zwitterionic structures [4,5]. However, Drayßa et al have just found an opposite trend (increasing stability of charge solvated complexes with increasing size of metal ion) for some aliphatic amino acids, based on their experimental IR spectra and calculations [9]. In the complex ions combined with peptides, alkali metal ions can form multidentate bonds to carbonyl oxygen atoms in the backbone and can stabilize helical structures in the gas phase [10,11].…”

Consecutive losses of two benzyl radicals from the [M + Na]+ adduct ions of di- and tri(benzyloxy)benzenes under ESI/CID conditions

“…Representing neither protonated [3,4] nor radical cationic [5,6] species, the fragmentation chemistry of such [M + metal] + ions is not well understood and a rich source of surprise. A growing number of reports deal with this topic [7][8][9][10][11] and the need for new or extended fragmentation rules is obvious, given the fact that electrospray ionization, in particular, mostly generates even-electron parent ions (so-called "quasi-molecular ions") [12,13] whose fragmentation under collision activation conditions deviates strongly from the well established rules of organic mass spectrometry [14][15][16][17][18][19][20].…”

Infrared Multiple Photon Dissociation Action Spectroscopy and Theoretical Studies of Triethyl Phosphate Complexes: Effects of Protonation and Sodium Cationization on Structure

“…Instead, smaller, more manageable complexes can be chosen to represent critical regions of the overall system, acting as useful models that can be used to probe and understand various features of macroscopic structure. Interactions within proteins are often studied in terms of constituent amino acids and small peptides, as demonstrated by recent work done in a variety of labs, including our own [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. Similarly, nucleic acids are conveniently broken down into their component nucleobases, nucleotides, nucleosides, and phosphate ester derivatives.…”