1167413-03-7Relevant academic research and scientific papers
Tyrosine deprotonation yields abundant and selective backbone cleavage in peptide anions upon negative electron transfer dissociation and ultraviolet photodissociation
Shaw, Jared B.,Ledvina, Aaron R.,Brodbelt, Jennifer S.,Zhang, Xing,Julian, Ryan R.
, p. 15624 - 15627,4 (2012)
Tyrosine deprotonation in peptides yields preferential electron detachment upon NETD or UVPD, resulting in prominent N-Cα bond cleavage N-terminal to the tyrosine residue. UVPD of iodo-tyrosine-modified peptides was used to generate localized radicals on neutral tyrosine side chains by homolytic cleavage of the C-I bond. Subsequent collisional activation of the radical species yielded the same preferential cleavage of the adjacent N-terminal N-Cα bond. LC-MS/MS analysis of a tryptic digest of BSA demonstrated that these cleavages are regularly observed for peptides when using high-pH mobile phases.
Exploring radical migration pathways in peptides with positional isomers, deuterium labeling, and molecular dynamics simulations
Zhang, Xing,Julian, Ryan R.
, p. 524 - 533 (2013/07/26)
One of the keys for understanding radical directed dissociation in peptides is a detailed knowledge of the factors that mediate radical migration. Peptide radicals can be created by a variety of means; however, in most circumstances, the originally created radicals must migrate to alternate locations in order to facilitate fragmentation such as backbone cleavage or side chain loss. The kinetics of radical migration are examined herein by comparing results from ortho-, meta-, and para-benzoyl radical positional isomers for several peptides. Isomers of a constrained cyclic peptide generated by several orthogonal radical initiators are also probed as a function of charge state. Cumulatively, the results suggest that small changes in radical position can significantly impact radical migration, and overall structural flexibility of the peptide is also an important controlling factor. A particularly interesting pathway for the peptide RGYALG that is sensitive to ortho versus meta or para substitution was fully mapped out by a suite of deuterium labeled peptides. This data was then used to optimize parameters in molecular dynamics-based simulations, which were subsequently used to obtain further insight into the structural underpinnings that most strongly influence the kinetics of radical migration. [Figure not available: see fulltext.]
