IRMPD Spectroscopy of Homo- and Heterochiral Asparagine Proton-Bound Dimers in the Gas Phase.

Åke Andersson,Rianne E Van Outersterp,Vitali Zhaunerchyk,Kas J Houthuijs,Mathias Poline,Jos Oomens,Giel Berden

doi:10.1021/acs.jpca.1c05667

Abstract

We investigate gas-phase structures of homo- and heterochiral asparagine proton-bound dimers with infrared multiphoton dissociation (IRMPD) spectroscopy and quantum-chemical calculations. Their IRMPD spectra are recorded at room temperature in the range of 500–1875 and 3000–3600 cm–1. Both varieties of asparagine dimers are found to be charge-solvated based on their IRMPD spectra. The location of the principal intramolecular H-bond is discussed in light of harmonic frequency analyses using the B3LYP functional with GD3BJ empirical dispersion. Contrary to theoretical analyses, the two spectra are very similar.

Highlights

Investigation of amino acids (AAs) and their oligomers are of interest because of their fundamental role in biology
Protonation of an AA dramatically alters its structure by changing which inter- and intramolecular noncovalent interactions (NCI) to the environment are preferred.[1−7] Gas-phase proton-bound AA dimers, meaning pairs of AAs with one extra H+, have gained significant interest, both from experimental and theoretical perspectives[8−16] because they contain the complexity of inter- and intramolecular NCI, despite their small size
The infrared multiple photon disassociation (IRMPD) spectra of homo- and heterochiral proton-bound asparagine dimers were obtained in the frequency ranges of 500−1875 and 3000−3600 cm−1

Summary

INTRODUCTION

Investigation of amino acids (AAs) and their oligomers are of interest because of their fundamental role in biology. Protonation of an AA dramatically alters its structure by changing which inter- and intramolecular noncovalent interactions (NCI) to the environment are preferred.[1−7] Gas-phase proton-bound AA dimers, meaning pairs of AAs with one extra H+, have gained significant interest, both from experimental and theoretical perspectives[8−16] because they contain the complexity of inter- and intramolecular NCI, despite their small size. This makes them useful model systems for the NCI in proteins. Simultaneous measurement is achieved by mass labeling the heterochiral dimer

METHODS

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RESULTS AND DISCUSSION

CONCLUSIONS

■ ACKNOWLEDGMENTS

■ REFERENCES