title: Valence anions of N-acetylproline in the gas phase: computational and anion photoelectron spectroscopic studies.
abstract: We report the photoelectron spectrum of anionic N-acetylproline, (N-AcPro)(-), measured with 3.49 eV photons. This spectrum, which consists of a band centered at an electron binding energy of 1.4 eV and a higher energy spectral tail, confirms that N-acetylproline forms a valence anion in the gas phase. The neutrals and anions of N-AcPro were also studied computationally at the B3LYP∕6-31++G(d,p) level. Based on the calculations, we conclude that the photoelectron spectrum is due to anions which originated from proton transfer induced by electron attachment to the π* orbital localized at the acetyl group of N-AcPro. We also characterized the energetics of reaction paths leading to pyrrolidine ring opening in the anionic N-AcPro. These data suggest that electron induced decomposition of peptides/proteins comprising proline strongly depends on the presence of proton donors in the close vicinity to the proline residue.
authors.affiliation: Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland.
authors.forename: Lidia
authors.initials: L
authors.lastname: Chomicz
authors.forename: Janusz
authors.initials: J
authors.lastname: Rak
authors.forename: Piotr
authors.initials: P
authors.lastname: Paneth
authors.forename: Michael
authors.initials: M
authors.lastname: Sevilla
authors.forename: Yeon Jae
authors.initials: YJ
authors.lastname: Ko
authors.forename: Haopeng
authors.initials: H
authors.lastname: Wang
authors.forename: Kit H
authors.initials: KH
authors.lastname: Bowen
mesh_terms: D000838:Anions; D004583:Electrons; D005740:Gases / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D011392:Proline / Q000031:analogs & derivatives* / Q000737:chemistry; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D000838:Anions; D005740:Gases; D011392:Proline; C055247:N-acetylproline