Identification and Quantification of Any Isoforms of Carbohydrates by 2D UV-MS Fingerprinting of Cold Ions

Abstract

Biological functionality of isomeric carbohydrates may differ drastically, making their identifications indispensible in many applications of life science. Due to the large number of isoforms, structural assignment of saccharides is challenging and often requires a use of different orthogonal analytical techniques. We demonstrate that isomeric carbohydrates of any isoforms can be distinguished and quantified using solely the library-based method of 2D UV-MS photofragmentation of cold ions. The two-dimensional "fingerprint" identities of UV transparent saccharides were revealed by photofragmentation of their non-covalent complexes with aromatic molecules. We assess the accuracy of the method by comparing the known relative concentrations of isomeric carbohydrates mixed in solution with the concentrations that were mathematically determined from the measured in the gas phase fingerprints of the complexes. For the tested sets with up to five isomers of di-to heptasaccharides, the root-mean-square deviation of 3-5% was typically achieved. This indicates the expected level of accuracy in analysis of unknown mixtures for isomeric carbohydrates of similar complexity.

Advanced tandem mass spectrometry in metabolomics and lipidomics—methods and applications

“…For example, Mucha et al [137] and Kirschbaum et al [138,139] used IR action spectroscopy of cooled ions to differentiate isomeric oligosaccharides and sphingolipids, respectively. Cold ion UVPD spectroscopy of isomeric ephedrines [140] and glycans [141] also revealed the potential of tandem MS performed with tunable-laser systems to distinguish isomeric metabolites and lipids. The biggest challenge for all advanced tandem MS methods and especially for spectroscopic tools is the integration into routine LC-MS n and MSI workflows.…”

Differentiation of disaccharide isomers via a combination of IR and UV photodissociation mass spectrometry

“…For the latter case mentioned above, the methods of gas‐phase photon action spectroscopy in the IR or UV regions provide unique and valuable information about their structures and relative dynamics 38–50 . However, the collection of spectra usually needs longer time and higher requirements for researchers.…”

Identification of Isomeric Lipids by UV Spectroscopy of Noncovalent Complexes with Aromatic Molecules

“…14 The amazing isomeric specificity of the UV absorption by tyrosine (Tyr) or a tyramine aromatic sensor in such complexes enabled the identification of all types of isomers of carbohydrates. 15 The essential feature that allows for the high sensitivity of these sensors to the isoforms of the carbohydrates is the intrinsic richness of the latter biomolecules in OH functional groups, which may form strong hydrogen bonds with the hydroxyl group of the Tyr aromatic ring. 14 Inductive polarization of the electronic π system through these interactions leads to certain spectroscopic changes, which can be isomer-specific.…”

“…31 Our implementation of the UV cold ion spectroscopy method has been described elsewhere. 15,32 Briefly, the complexes are formed in water/methanol solution and brought to the gas phase using a super "gentle" tripleskimmer electrospray ionization source. 33 The softness of the source is essential to preserve the weakly bound lipid− aromatic complexes during ionization: up to half of the lipids transferred to the gas phase appear in the complexes.…”

“…The changes mutually reflect the structural details of the molecules and, potentially, can be detected by spectroscopy. , This property of noncovalent interactions was recently explored for identifications of isomeric carbohydrates by UV spectroscopy of their complexes with aromatic “sensor” molecules . The amazing isomeric specificity of the UV absorption by tyrosine (Tyr) or a tyramine aromatic sensor in such complexes enabled the identification of all types of isomers of carbohydrates . The essential feature that allows for the high sensitivity of these sensors to the isoforms of the carbohydrates is the intrinsic richness of the latter biomolecules in OH functional groups, which may form strong hydrogen bonds with the hydroxyl group of the Tyr aromatic ring .…”