Using non-covalent complexes to direct the fragmentation of glycosidic bonds in the gas phase

Abstract

An investigation of the gas phase chemistry of proton bound oligosaccharide (S)-ligand (L) non-covalent complexes, [S ϩ H ϩ L] ϩ has been carried out using electrospray ionization (ESI) and tandem mass spectrometry in a quadrupole ion trap. When subjected to collision-inducedϩ complexes undergo a range of reactions that can be broadly classified into three main types: (1) Simple dissociation into the individual monomers; (2) cleavage of the oligosaccharide to form B-type sequence ions; (3) cleavage of the ligand species. The second type of reaction is particularly interesting as it can produce a "ladder series" of [B x ϩ L] ϩ ions via ligand induced oligosaccharide bond cleavage. This novel gas phase reaction greatly simplifies the sequencing of oligosaccharides. Both the oligosaccharide and ligand were found to influence the type of reaction pathway observed, with the "ladder series" of [B x ϩ L] ϩ ions being favored for permethylated oligosaccharides and for bifunctional ligands. Cytosine is a particularly good ligand at facilitating the formation of [B x ϩ L] ϩ ions. Analogies with condensed phase chemistry of sugars is made and a potential mechanism for ligand induced oligosaccharide bond cleavage is proposed. (J Am Soc Mass Spectrom 2004, 15, 715-724)

Investigation of multiple binding sites on ribonuclease A using nano‐electrospray ionization mass spectrometry

“…Similar decomposition patterns have previously been reported for double-stranded DNA, which was shown to not dissociate into single-stranded DNA, but rather to lose a nucleobase. 23 Furthermore, it can be concluded that the dissociation pathway is the same as for free monobasic cytosinecontaining oligonucleotides, 24,25 but different from the dissociation of CMP and CTP, which dissociate from RNAse without breaking covalent bonds. This clearly suggests that cooperative non-covalent interactions can result in an interaction strength of a magnitude similar to that for covalent interactions.…”

Sources of artefacts in the electrospray ionization mass spectra of saturated diacylglycerophosphocholines: From condensed phase hydrolysis reactions through to gas phase intercluster reactions

“…For example, noncovalent complexes of phosphate anions of biological interest undergo condensation reactions including: diphosphate formation [2], triphosphate formation [3], and phosphorylation of peptides [4]. Noncovalent complexes between nucleobases and sugars promote the cleavage of saccharide bonds via condensation reactions [5]. Furthermore, a number of tetralkylammonium salts undergo gas-phase S N 2 reactions, including those involving organic counter ions (eq 1a) [6,7], inorganic counter ions (eq 2) [8], counter ions derived from biomolecules such as peptides (eq 3a, b) [9], DNA (eq 4a) [10], and glycerophosphocholine adducts (eq 5) [11].…”

Interplay of H‐Bonds with Aromatics in Isolated Complexes Identifies Isomeric Carbohydrates

“…Although aromatics, but not carbohydrates, are efficiently protonated in solution, the highly abundant protonated saccharides and their fragments appear in the photofragment MS of the complexes (Figures B, B, and B). These observations suggest a proton and energy transfer from the aromatics to the saccharides in the electronic ground and/or, upon UV excitation, excited state of the complexes. Protonated aromatics are the most abundant photofragments observed for mono‐ (for example, d ‐/ l ‐glucose; Figure S5) and disaccharaides (Figure S6) that do not contain NAc groups.…”