4 research outputs found
Ion-Induced Dipole Interactions and Fragmentation Times : C -C Chromophore Bond Dissociation Channel
The fragmentation times corresponding to the loss of the chromophore
(C-- C bond dissociation channel) after photoexcitation at 263
nm have been investigated for several small peptides containing tryptophan or
tyrosine. For tryptophan-containing peptides, the aromatic chromophore is lost
as an ionic fragment (m/z 130), and the fragmentation time increases with the
mass of the neutral fragment. In contrast, for tyrosine-containing peptides the
aromatic chromophore is always lost as a neutral fragment (mass = 107 amu) and
the fragmentation time is found to be fast (\textless{}20 ns). These different
behaviors are explained by the role of the postfragmentation interaction in the
complex formed after the C--C bond cleavage
Source, piÚge à ions, laser, détection en coïncidence ; nouvel outil expérimental
National audienc
UV photofragmentation dynamics of protonated cystine: disulfide bond rupture
International audienceDisulfide bonds (SâS) play a central role in stabilizing the native 9 structure of proteins against denaturation. Experimentally, identification of these linkages in peptide and protein structure characterization remains challenging. UV photodissociation (UVPD) can be a valuable tool in identifying disulfide linkages. Here, the SâS bond acts as a UV chromophore and absorption of one UV photon corresponds to a ÏâÏ* transition. We have investigated the photodissociation dynamics of protonated cystine, which is a dimer of two cysteines linked by a disulfide bridge, at 263 nm (4.7 eV) using a multicoincidence technique in which fragments coming from the same fragmentation event are detected. Two types of bond cleavages are observed corresponding to the disulfide (SâS) and adjacent CâS bond ruptures. We show that the SâS cleavage leads to three different fragmentions via three different fragmentation mechanisms. The UVPD results are compared to collision-induced dissociation (CID) and electron-induced dissociation (EID) studies