Photoelectron spectroscopy of the deprotonated tryptophan anion: the contribution of deprotomers to its photodetachment channels

0585161 - ÚFCH JH 2025 RIV GB eng J - Journal Article
Gibbard, J. A. - Kellow, C. S. - Verlet, Jan Raf Rogier
Photoelectron spectroscopy of the deprotonated tryptophan anion: the contribution of deprotomers to its photodetachment channels.
Physical Chemistry Chemical Physics. Roč. 26, č. 15 (2024), s. 12053-12059. ISSN 1463-9076. E-ISSN 1463-9084
R&D Projects: GA MŠMT EH22_008/0004649
Grant - others:Ministerstvo školství, mládeže a tělovýchovy(CZ) CZ.02.01.01/00/22_008/0004649
Institutional support: RVO:61388955
Keywords : uv absorption-band * basis-sets * acid * fluorescence * proteins * dynamics * tyrosine * spectra * atoms
OECD category: Physical chemistry
Impact factor: 3.3, year: 2022
Method of publishing: Open access
https://pubs.rsc.org/en/content/articlelanding/2024/cp/d4cp00309h

Photoelectron spectroscopy and electronic structure calculations are used to investigate the electronic structure of the deprotonated anionic form of the aromatic amino acid tryptophan, and its chromophore, indole. The photoelectron spectra of tryptophan, recorded at different wavelengths across the UV, consist of two direct detachment channels and thermionic emission, whereas the h nu = 4.66 eV spectrum of indole consists of two direct detachment features. Electronic structure calculations indicate that two deprotomers of tryptophan are present in the ion beam, deprotonation of the carboxylic acid group (Trp(i)-) or the N atom on the indole ring (Trp(ii)-). Strong similarities are observed between the direct detachment channels in the photoelectron spectra of tryptophan and indole, which in conjunction with electronic structure calculations, indicate that electron loss from Trp(ii)- dominates this portion of the spectra. However, there is some evidence that direct detachment of Trp(i)- is also observed. Thermionic emission is determined to predominantly arise from the decarboxylation of Trp(i)-, mediated by the pi pi* excited state near lambda = 300 nm, which results in an anionic fragment with a negative electron affinity that readily autodetaches.
Permanent Link: https://hdl.handle.net/11104/0352903