报告题目：Gas-phase spectroscopy of small biologically relevant molecules

报告人： Vitali Zhaunerchyk 副教授（Gothenburg University）

报告时间：2023年09月04日（星期一）15：00-16：00

报告地点：北洋园校区 32 教 140 室

报告摘要：

Gas-phase IR spectroscopy provides a bottom-up approach to studying the structures of biomolecules and their interactions at the atomic level. In this approach, biomolecular building blocks, such as amino acids and peptides (miniature proteins), are investigated with the aim to extrapolate the results to macromolecules. The gas phase enables the isolation of molecules from ambient species thus studying intrinsic properties. Furthermore, the obtained results from gas-phase IR spectroscopy can directly be combined with quantum chemical calculations.

A well-established way to perform IR spectroscopy for neutral gas-phase molecules is UV-IR ion-dip spectroscopy. The main advantage of this technique is that it allows measuring IR spectra for individual conformers. However, it can only be implemented for species containing UV chromophores. As only 3 proteinogenic amino acids contain chromophores (Phe, Tyr, Trp), the applicability of this method to peptides is rather limited. To overcome this obstacle, we have developed a new approach, IRMPD-VUV spectroscopy, which can be implemented for molecules of arbitrary structure.

In my talk, I will present the ion-dip UV-IR and IRMPD-VUV methods as well as the theoretical tools we employ to deduce molecular structures from the experimental measurements. We have implemented IRMPD-VUV to two dipeptides, Gly-Gly and Ala-Ala, and pentapeptide, Ala-Ala-Ala-Ala-Ala to investigate competition between folded and extended conformers. I will also demonstrate the results from IRMPD spectroscopy for homo- and hetero-chiral proton-bound amino acid dimers. The experimental results which I will present were obtained experimentally employing the CLIO and FELIX free electron lasers as IR light.

参考文献：

[1] Photochemical Ring-Opening Reaction of 1,3-Cyclohexadiene: Identifying the True Reactive State. O. Travnikova, et al., J. Am. Chem. Soc. 144, 21878 (2022).

[2] Acetylacetone photodynamics at a seeded free-electron laser. R. J. Squibb et al., Nature Communications 9, 2041 (2018).

[3] Infrared Action Spectroscopy of Low-Temperature Neutral Gas-Phase Molecules of Arbitrary Structure. V. Yatsyna et al., Phys. Rev. Lett. 117, 118101 (2016).