Chiral discrimination between tyrosine and β-cyclodextrin revealed by cryogenic ion trap infrared spectroscopy. Issue 43 (11th September 2020)

• Record Type: Journal Article
• Authors: Hirata, Keisuke; Mori, Yuta; Ishiuchi, Shun-ichi; Fujii, Masaaki; Zehnacker, Anne
• Is Part Of: Physical chemistry chemical physics. Volume 22:Issue 43(2020)
• Page Start: 24887
• Page End: 24894
• Publication Date: 2020-09-11
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d0cp02968h
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Cryogenic ion trap infrared spectroscopy reveals that different binding motifs between the two enantiomers of protonated tyrosine and permethylated β-cyclodextrin result in chiral discrimination. Abstract : Complexes of permethylated β-cyclodextrin (β-MCD) with the two enantiomers of protonated tyrosine (l - and d -TyrH + ) are studied by cryogenic ion trap infrared photo-dissociation spectroscopy. The vibrational spectra in the OH/NH stretch and fingerprint regions are assigned based on density functional theory calculations. The spectrum of both l - and d -TyrH + complexes contains features characteristic of a first structure with ammonium and acid groups of the amino acid simultaneously interacting with the β-MCD, the phenolic OH remaining free. A second structure involving additional interaction between the phenolic OH and the β-MCD is observed only for the complex with d -TyrH + . The larger abundance of the d -TyrH + complex in the mass spectrum is tentatively explained in terms of (1) better insertion of d -TyrH + within the cavity with the hydrophobic aromatic moiety less exposed to hydrophilic solvent molecules and (2) a stiff structure involving three interaction points, namely the ammonium, the phenolic OH and the carboxylic acid OH, which is not possible for the complex with l -TyrH + . The recognition process does not occur through size effects that induce complementarity to the host molecule but specific interactions. These results provide a comprehensive understanding of how the cyclodextrin recognises a chiral biomolecule.