Evaluation and determination of the cyclofructans–amino acid complex binding pattern by electrospray ionization mass spectrometry

Abstract

The noncovalent complex interactions between cyclofructans, a new class of cyclic oligosaccharide hosts, and various amino acids have been characterized by means of electrospray ionization mass spectrometry and nuclear magnetic resonance. The 1 : 1 stoichiometry of cyclofructans and amino acid complexes was confirmed by their mass-to-charge ratio in positive mode. Cyclofructans (CFs)-amino acid complexes and cyclodextrin-amino acid complexes exhibited distinctive different fragment behaviors in collision-induced dissociation experiments. Coupled with the results of (1) H NMR and nuclear overhauser effect spectroscopy, cyclofructan-amino acid complexes were deduced to be rim complexes via formation hydrogen bondin and ion-dipole forces. The interaction pattern could be controlled by changing the pH condition. In neutral solution, amino acids are located on the positive side of CFs, although moved to the negative side pocket constructed by 3-OH oxygen of furanose ring and the crown ether oxygen in acid condition. In addition, theory calculation for geometry optimization of Trp and CFs was performed, which was in good agreement with the experimental results.

Quantifying non‐covalent binding affinity using mass spectrometry: A systematic study on complexes of cyclodextrins with alkali metal cations

“…Research on non‐covalent interactions between metal cations and biological macromolecules such as proteins, nucleotides and oligosaccharides has received considerable attentions in the past few years due to their potential applications in pharmaceutical industry. Burt and Fridgen recently reviewed their research into electrospray ionization mass spectrometry (ESI‐MS) techniques to probe the structure and reactivity of metal‐cationized biological ions including proteins, nucleobases and nucleotides, and highlighted the intrinsic structural properties and behavior of these complexes.…”

Gas-Phase Fragmentation of Cyclic Oligosaccharides in Tandem Mass Spectrometry

“…Intact CFs also form 1:1 aggregates with alkali metal ions (for extensive ESI MS and DFT molecular modeling studies see [22]). CFs possesses hydrophobic cavities (however, not as prominent as those of CDs) and, hence, are capable of forming inclusion complexes with hydrophobic compounds, e.g., amino acids [23] (compare to CDs: [24,25,26]), so despite a different carbohydrate composition, CDs and CFs have similar properties.…”