Francesco Falvo, Lukas Fiebig, M. Schäfer
Nov 15, 2013
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0
Influential Citations
12
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Journal
International Journal of Mass Spectrometry
Abstract
Abstract 4,4′-Azobis[4-cyanopentanoic] acid, a symmetrical free radical initiator, is transformed in the bis- N -succinimidyl-active ester (azoXL) and utilized for peptide cross-linking (XL). The azoXL-reagent reacts with amine functionalities and performs upon collision induced dissociation (CID) exclusively the loss of N 2 leading to the formation of two radical sites. (+)ESI-MS n product-ion spectra of the protonated molecular ion of two model peptides (MRFA and RKDVY) interconnected N -terminally by 4,4′-azobis[4-cyanopentanoic] acid show characteristically mass-shifted product ions and neutral losses (N 2 = 28 Da; 2-methylacrylonitrile = 67 Da), potentially useful for identification of XL derivatized peptides. Additionally, CID fragmentation reactions lead to the formation of sequence-specific fragment ions, allowing primary structure elucidation. The presented results demonstrate the potential of azo-compounds as CID-labile XL-reagents for tandem MS analysis. The fragmentation behaviour of peptides (MRFA, RKDVY and Substance P) derivatized with the azoXL reagent is studied by MS n , exact ion mass measurements and ion-molecule reactions (IMRs) with allyliodide and dimethyl disulfide.