Competition between diketopiperazine and oxazolone formation in water loss products from protonated ArgGly and GlyArg

TitleCompetition between diketopiperazine and oxazolone formation in water loss products from protonated ArgGly and GlyArg
Publication TypeJournal Article
Year of Publication2012
AuthorsS. Zou, J. Oomens, N.C Polfer
JournalInternational Journal of Mass Spectrometry
Volume316
Pagination12-17
Date PublishedApr
Type of ArticleArticle
ISBN Number1387-3806
KeywordsB(2) IONS, B(5), CID, COLLISION-INDUCED DISSOCIATION, DENSITY-FUNCTIONAL THEORY, DFT, FRAGMENTATION PATHWAYS, GAS-PHASE, HYDROGEN/DEUTERIUM EXCHANGE, INFRARED-SPECTROSCOPY, ION, IONS, IR spectroscopy, MAIN, MULTISTAGE MASS-SPECTROMETRY, OXAZOLONE, SPECTROSCOPY, TRYPTIC PEPTIDES, Vibrational spectra
Abstract

The mechanism of peptide "b" fragment formation in collision-induced dissociation (CID) is generally understood as a nucleophilic attack from a carbonyl oxygen onto the electron deficient carbon of the dissociating amide bond forming a five-membered oxazolone ring structure. Nonetheless, other nucle-ophiles, such as the N-terminus and side-chain moieties (e.g., imidazole, guanidine), can in principle engage in a nucleophilic attack to induce amide backbone cleavage. Here, we apply a combination of infrared multiple photon dissociation (IRMPD) spectroscopy and computational chemistry to characterize the water loss, [M+H-H2O](+), product ions from protonated ArgGly and GlyArg. IRMPD spectra for [M+H-H2O](+) from ArgGly and GlyArg differ in the presence and absence of a characteristic band at 1885 cm(-1), which is indicative of an oxazolone structure for ArgGly. The remaining parts of the vibrational spectra are consistent with the vibrational signatures of diketopiperazine structures. Conversely, there is no match between the experimental spectra and any of the putative structures arising from guanidine side-chain attack. These results show that the presence of a basic residue, such as arginine, facilitates the formation of diketopiperazine structures, and that residue order matters in the competition between diketopiperazine and oxazolone pathways. (c) 2012 Published by Elsevier B.V.

URLhttp://www.sciencedirect.com/science/article/pii/S1387380612000036
DOI10.1016/j.ijms.2011.12.020
Division

GUTHz

Department

Moldyn

PID

5f9f02fe157236edd304da7c1412f69b

Alternate TitleInt. J. Mass Spectrom.

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