Near-UV Photodissociation of Tryptic Peptide Cation Radicals. Scope and Effects of Amino Acid Residues and Radical Sites

作者：Nguyen Huong T H; Turecek Frantisek

来源：Journal of the American Society for Mass Spectrometry, 2017, 28(7): 1333-1344.

DOI：10.1007/s13361-016-1586-7

• Electron transfer dissociation
• Tryptic peptides
• Cation-radical fragments ions
• Photodissociation
• Excited states

Peptide cation-radical fragment ions of the z-type, [. AXAR+], [. AXAK+], and [. XAR+], where X = A, C, D, E, F, G, H, K, L, M, N, P, Y, andW, were generated by electron transfer dissociation of peptide dications and investigated by MS3-nearultraviolet photodissociation (UVPD) at 355 nm. Laser-pulse dependence measurements indicated that the ion populations were homogeneous for most X residues except phenylalanine. UVPD resulted in dissociations of backbone CO -NH bonds that were accompanied by hydrogen atom transfer, producing fragment ions of the [yn]+ type. Compared with collision-induced dissociation, UVPD yielded less sidechain dissociations even for residues that are sensitive to radical-induced side-chain bond cleavages. The backbone dissociations are triggered by transitions to second (B) excited electronic states in the peptide ion R-CH. -CONH-chromophores that are resonant with the 355-nm photon energy. Electron promotion increases the polarity of the B excited states, R-CH+-C. (O-) NH-, and steers the reaction to proceed by transfer of protons from proximate acidic Ca and amide nitrogen positions.

• 出版日期2017-7