UV Photofragmentation Dynamics of Protonated Cystine: Disulfide Bond Rupture.
Disulfide bonds (S-S) play a central role in stabilizing the native 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 S-S bond acts as a UV chromophore and absorption of one UV photon corresponds to a σ-σ* 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 (S-S) and adjacent C-S bond ruptures. We show that the S-S cleavage leads to three different fragment ions via three different fragmentation mechanisms. The UVPD results are compared to collision-induced dissociation (CID) and electron-induced dissociation (EID) studies.
†Institut des Sciences Moléculaires d'Orsay, CNRS UMR 8214, Université Paris Sud, F-91405 Orsay Cedex, France.
Satchin
S
Soorkia
†Institut des Sciences Moléculaires d'Orsay, CNRS UMR 8214, Université Paris Sud, F-91405 Orsay Cedex, France.
Christophe
C
Dehon
†Institut des Sciences Moléculaires d'Orsay, CNRS UMR 8214, Université Paris Sud, F-91405 Orsay Cedex, France.
S Sunil
SS
Kumar
†Institut des Sciences Moléculaires d'Orsay, CNRS UMR 8214, Université Paris Sud, F-91405 Orsay Cedex, France.
Mélanie
M
Pedrazzani
†Institut des Sciences Moléculaires d'Orsay, CNRS UMR 8214, Université Paris Sud, F-91405 Orsay Cedex, France.
Emilie
E
Frantzen
†Institut des Sciences Moléculaires d'Orsay, CNRS UMR 8214, Université Paris Sud, F-91405 Orsay Cedex, France.
Bruno
B
Lucas
†Institut des Sciences Moléculaires d'Orsay, CNRS UMR 8214, Université Paris Sud, F-91405 Orsay Cedex, France.
Michel
M
Barat
†Institut des Sciences Moléculaires d'Orsay, CNRS UMR 8214, Université Paris Sud, F-91405 Orsay Cedex, France.
Jacqueline A
JA
Fayeton
‡Aix Marseille Université, CNRS, PIIM UMR 7375, 13397 Marseille Cedex 20, France.
Christophe
C
Jouvet
UV photodissociation; disulfide bond; excited states; fragmentation mechanism