000202219 001__ 202219
000202219 005__ 20181203023628.0
000202219 0247_ $$2doi$$a10.1063/1.4897158
000202219 022__ $$a0021-9606
000202219 02470 $$2ISI$$a000344346000026
000202219 037__ $$aARTICLE
000202219 245__ $$aFragmentation mechanism of UV-excited peptides in the gas phase
000202219 260__ $$bAmerican Institute of Physics$$c2014$$aMelville
000202219 269__ $$a2014
000202219 300__ $$a12
000202219 336__ $$aJournal Articles
000202219 520__ $$aWe present evidence that following near-UV excitation, protonated tyrosine- or phenylalanine–containing peptides undergo intersystem crossing to produce a triplet species. This pathway competes with direct dissociation from the excited electronic state and with dissociation from the electronic ground state subsequent to internal conversion. We employ UV-IR double-resonance photofragment spectroscopy to record conformer-specific vibrational spectra of cold peptides pre-excited to their S1 electronic state. The absorption of tunable IR light by these electronically excited peptides leads to a drastic increase in fragmentation, selectively enhancing the loss of neutral phenylalanine or tyrosine side-chain, which are not the lowest dissociation channels in the ground electronic state. The recorded IR spectra evolve upon increasing the time delay between the UV and IR pulses, reflecting the dynamics of the intersystem crossing on a timescale of ∼80 ns and <10 ns for phenylalanine- and tyrosine-containing peptides, respectively. Once in the triplet state, phenylalanine-containing peptides may live for more than 100 ms, unless they absorb IR photons and undergo dissociation by the loss of an aromatic side-chain. We discuss the mechanism of this fragmentation channel and its possible implications for photofragment spectroscopy and peptide photostability.
000202219 6531_ $$aion spectroscopy
000202219 6531_ $$aultraviolet spectra
000202219 6531_ $$amass spectrometry
000202219 6531_ $$aphotodissociation
000202219 6531_ $$ainfrared spectra
000202219 6531_ $$abiomolecules
000202219 700__ $$0242825$$g196232$$aZabuga, Aleksandra
000202219 700__ $$0246402$$g221188$$aKamrath, Michael Zachary
000202219 700__ $$0242817$$g104570$$aBoyarkin, Oleg V.
000202219 700__ $$0242829$$g106239$$aRizzo, Thomas R.
000202219 773__ $$j141$$tJournal of Chemical Physics$$q154309
000202219 909C0 $$xU10106$$0252096$$pLCPM
000202219 909CO $$pSB$$particle$$ooai:infoscience.tind.io:202219
000202219 917Z8 $$x106239
000202219 917Z8 $$x106239
000202219 937__ $$aEPFL-ARTICLE-202219
000202219 973__ $$rREVIEWED$$sPUBLISHED$$aEPFL
000202219 980__ $$aARTICLE