title: Excited state dynamics and fragmentation channels of the protonated dipeptide H2N-Leu-Trp-COOH.
abstract: The excited state dynamics of the isolated and protonated peptide H(2)N-Leu-Trp-COOH are analyzed by fs pump-probe spectroscopy. The peptides are brought into the gas phase by electrospray ionization, and fs pump-probe excitation is detected by fragment ion formation. The pump laser addressed the excited pipi* state of the indole chromophore of the amino acid tryptophan. The subsequent excited state dynamics agreed with a biexponential decay with time constants of 500 fs and 10 ps. This is considerably shorter than the lifetime of neutral tryptophan in solution and in proteins, but similar to isolated, protonated tryptophan. Several models are discussed to explain the experimental results but the detailed quenching mechanism remains unresolved.
authors.affiliation: Max Born Institute, Max-Born-Str. 2a, 12489 Berlin, Germany. nolting@mbi-berlin.de
authors.forename: Dirk
authors.initials: D
authors.lastname: Nolting
authors.forename: Thomas
authors.initials: T
authors.lastname: Schultz
authors.forename: I V
authors.initials: IV
authors.lastname: Hertel
authors.forename: Rainer
authors.initials: R
authors.lastname: Weinkauf
mesh_terms: D003198:Computer Simulation; D004151:Dipeptides / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D008956:Models, Chemical; D008958:Models, Molecular; D011522:Protons
chemical_list: D004151:Dipeptides; D011522:Protons