Influence of basic residues on dissociation kinetics and dynamics of singly protonated peptides: time-resolved photodissociation study

摘要

Production yields in postsource decay and time-resolved photodissociation at 193 and 266 nm were measured for some peptide ions with lysine ([KF6 + H](+), [F6K + H](+), and [F3KF3 + H](+)) formed by matrix-assisted laser desorption ionization. The critical energy (E-0) and entropy (Delta S double dagger) were determined by RRKM fitting of the data. The results were similar to those found previously for peptide ions with histidine. To summarize, the presence of a basic residue, histidine or lysine, inside a peptide ion retarded its dissociation by lowering Delta S double dagger. On the basis of highly negative Delta S double dagger, presence of intramolecular interaction involving a basic group in the transition structure was proposed.