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Influence of basic residues on dissociation kinetics and dynamics of singly protonated peptides: time-resolved photodissociation study
- Yoon, So Hee, Moon, Jeong Hee, Chung, Yeon Ji, Kim, Myung Soo
- Journal of mass spectrometry 2009 v.44 no.10 pp. 1532-1537
- desorption, dissociation, energy, entropy, histidine, ionization, ions, lysine, mass spectrometry, peptides, photolysis
- Product ion 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 (E₀) and entropy (ΔS[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 ΔS[double dagger]. On the basis of highly negative ΔS[double dagger], presence of intramolecular interaction involving a basic group in the transition structure was proposed.